the foregoing contents of the invention will be further explained in details by means of experimental examples hereinafter , but it should not be understood that the scope of the foregoing subject of the invention is only limited to the following examples , and any technology implemented based on the foregoing contents of the invention shall all fall within the scope of the invention . ( 1 ) 51 . 07 g of d , l - lactide and 50 . 57 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 7 h under 100 □, nitrogen displacement was performed , d , l - lactide was added , and 0 . 2 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 096 mpa , a reaction temperature was maintained at 100 ° c ., nitrogen displacement was performed for three times after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , then the temperature was raised to 140 ° c ., and reaction was performed for 12 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 25 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ), and stirred for 30 min ; then 510 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; then standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , thus obtaining the methoxypolyethylene glycol - polylactic acid block copolymer ; refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 75 %. the obtained polymer was characterized using nuclear magnetic resonance and gel chromatography , wherein the results were as shown in fig1 and fig2 . fig1 is the characterization of various hydrogens in the methoxypolyethylene glycol - polylactic acid block copolymer , proving that the methoxypolyethylene glycol - polylactic acid block copolymer is synthesized . the detection results of fig2 are as follows : mp : 6330 ; mn : 5887 ; mw : 6374 ; mz : 6873 ; m z + i : 7393 ; mv : 6301 ; and pdi : 1 . 08272 . ( 1 ) 48 . 77 g of d , l - lactide and 51 . 27 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 5 h under 120 ° c ., nitrogen displacement was performed , d , l - lactide was added , and then 0 . 048 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 095 mpa , a reaction temperature was maintained at 120 ° c ., nitrogen displacement was performed for three times after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and protected by nitrogen , then the temperature was raised to 140 ° c ., and reaction was performed for 14 h , thus obtaining a pale yellow clear liquid after the reaction was completed . ( 2 ) 29 ml of methylene chloride was added into the foregoing pale yellow clear liquid for dissolution , and was stirred and dissolved ; then 586 ml of anhydrous ice ethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 5 ° c ., then vacuum drying was performed after suction filtration . refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 85 %. ( 1 ) 47 . 53 g of d , l - lactide and 52 . 17 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 7h under 130 ° c ., nitrogen displacement was performed , 0 . 3 g of catalyst stannous octoate was added and then d , l - lactide was added , evacuation was performed to a vacuum degree of 0 . 093 mpa , a reaction temperature was maintained at 130 ° c ., nitrogen displacement was performed for three times after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , then the temperature was raised to 150 ° c ., and reaction was performed for 6 h , thus obtaining a pale yellow clear liquid after the reaction was completed . ( 2 ) 45 ml of methylene chloride was added into the foregoing pale yellow clear liquid in step ( 1 ), and was stirred and dissolved ; then 550 ml of anhydrous ice ethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., then vacuum drying was performed after suction filtration . refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 80 %. ( 1 ) 47 . 11 g of d , l - lactide and 52 . 85 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 4 h under 120 ° c ., d , l - lactide was added , and then 0 . 4 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 093 mpa , a reaction temperature was maintained at 120 ° c ., after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , then the temperature was raised to 130 ° c ., and reaction was performed for 18h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 40 ml of methylene chloride was added into the foregoing pale yellow clear viscous liquid obtained in step ( 1 ) for dissolution , and was stirred for 30 min ; then 500 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 80 %. ( 1 ) 45 . 91 g of d , l - lactide and 54 . 06 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 3 h under 120 ° c ., nitrogen displacement was performed , then d , l - lactide was added , and 0 . 25 g of catalyst stannous octoate was added , evacuation was performed , a reaction temperature was maintained at 120 ° c ., after the d , l - lactide was completely fused , nitrogen displacement was performed for three times , the reactor was ensured to have a negative pressure and was sealed , then the temperature was raised to 140 ° c ., and reaction was performed for 12 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 50 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ), and stirred for 30 min ; then 500 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 75 %. ( 1 ) 44 . 45 g of d , l - lactide and 55 . 68 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 5 h under 110 ° c ., nitrogen displacement was performed , then d , l - lactide was added , and 0 . 36 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 09 mpa , a reaction temperature was maintained at 110 ° c ., after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , the temperature was controlled to be raised to 140 ° c ., and reaction was performed for 14 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 60 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ), and stirred for 30 min ; then 660 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 80 %. ( 1 ) 39 . 51 g of d , l - lactide and 61 . 77 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 6h under 100 ° c ., nitrogen displacement was performed , then d , l - lactide was added , and 0 . 08 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 098 mpa , a reaction temperature was maintained at 100 ° c ., after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , the temperature was controlled to be raised to 140 ° c ., and reaction was performed for 12 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 50 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ), and stirred for 30 min ; then 540 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 70 %. ( 1 ) 42 . 17 g of d , l - lactide and 57 . 89 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 8 h under 100 ° c ., nitrogen displacement was performed , d , l - lactide was added , and then 0 . 45 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 095 mpa , a reaction temperature was maintained at 100 ° c ., after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , the temperature was controlled to be raised to 130 ° c ., and reaction was performed for 10 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 75 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ) for dissolution , and stirred for 30 min ; then 720 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 80 %. ( 1 ) 37 . 53 g of d , l - lactide and 62 . 71 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 6 h under 110 ° c ., nitrogen displacement was performed , then d , l - lactide was added , and 0 . 1 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 085 mpa , a reaction temperature was maintained at 110 ° c ., after the d , l - lactide was completely fused , evacuation was performed , the reactor was ensured to have a negative pressure and was sealed , the temperature was controlled to be raised to 140 ° c ., and reaction was performed for 6 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 40 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ), and stirred for 30 min ; then 556 ml of anhydrous ice diethyl ether was added , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 80 %. ( 1 ) 35 . 54 g of d , l - lactide and 64 . 68 g of methoxypolyethylene glycol 2000 were weighed for standby application , the methoxypolyethylene glycol 2000 was subjected to vacuum drying for 7 h under 100 ° c ., nitrogen displacement was performed , d , l - lactide was added , and then 0 . 08 g of catalyst stannous octoate was added , evacuation was performed to a vacuum degree of 0 . 098 mpa , nitrogen displacement was performed , and a reaction temperature was maintained at 100 ° c ., after the d , l - lactide was completely fused , evacuation was performed , and nitrogen protection is performed , the temperature was controlled to be raised to 140 ° c ., and reaction was performed for 12 h , thus obtaining a pale yellow clear viscous liquid after the reaction was completed . ( 2 ) 35 ml of methylene chloride was added into the pale yellow clear viscous liquid obtained in step ( 1 ) for dissolution , and stirred for 30 min ; then anhydrous ice diethyl ether was added according to a ratio of 5 to 1 between the volume of the anhydrous ice diethyl ether and the weight of the pale yellow clear viscous liquid ( i . e ., ml / g ) for extraction , and stirred for 30 min ; standing was performed for 12 h under 0 ° c ., vacuum drying was performed after suction filtration , and refining was performed for three times according to the foregoing operation process to obtain the methoxypolyethylene glycol - polylactic acid block copolymer , wherein the total yield was about 85 %. the block polymer prepared by the present invention is used as a carrier to prepare a drug nano - polymer micelle , wherein the steps are as follows : ( 1 ) 20 g of docetaxel , 400g ( mpeg2000 : pla = 1 : 0 . 99 ) of methoxypolyethylene glycol - polylactic acid block copolymer prepared in embodiment 1 , 4000 ml of water , and 400 ml of organic solvent acetonitrile were taken for standby application . ( 2 ) 1000 ml of acetonitrile was added into standby docetaxel for ultrasound dissolution ; then 400 g of methoxypolyethylene glycol - polylactic acid block copolymer was added for continuous dissolution , and then aseptic filtration was performed ; then rotary evaporation was performed for 2h under 50 ° c . and a rotation velocity of 80 r / min to boil off acetonitrile and obtain a docetaxel polymer gel film , 4000 g of 50 ° c . water was added quickly for vortex hydration , the temperature of the micelle solution was quickly reduced to 5 ° c . after complete hydration to obtain the micelle solution , then the micelle solution was subjected to aseptic filtration , sub - packaged and lyophilized . ( 1 ) fig3 is a cdcl 3 1 hnmr spectrum of the docetaxel nano - polymer micelle lyophilized preparation prepared in embodiment 11 , fig4 is a d 2 o 1 hnmr spectrum of the docetaxel polymer micelle lyophilized preparation prepared in embodiment 11 , and fig5 is a cdcl 3 1 hnm spectrum of the methoxypolyethylene glycol polylactic acid block copolymer prepared in embodiment 1 . results show that the docetaxel was encapsulated in the core of the micelle , and a characteristic absorption peak of the docetaxel in the 1hnmr spectrum of the micelle was not found . ( 2 ) a small quantity of the docetaxel nano - polymer micelle lyophilized preparation prepared in embodiment 11 , docetaxel and the methoxypolyethylene glycol polylactic acid prepared in embodiment 1 were taken to perform fourier transform infrared spectrum scanning , wherein results as shown in fig6 , fig7 and fig8 proved that the docetaxel was encapsulated in the core of the micelle , and a characteristic absorption peak of the docetaxel in the profile of the micelle was not found . ( 3 ) a small quantity of the docetaxel nano - polymer micelle lyophilized preparation prepared in embodiment 11 , docetaxel and the methoxypolyethylene glycol polylactic acid prepared in embodiment 1 were taken to perform thermal analysis scanning , wherein results as shown in fig9 , fig1 and fig1 proved that the docetaxel was encapsulated in the core of the micelle , and a characteristic absorption peak of the docetaxel in the thermal - scanning profile of the micelle was not found . embodiment 13 : encapsulation efficiency detection results of docetaxel nano - polymer micelle lyophilized preparation in different time after re - dissolving . a control drug was prepared according to a recipe 17 ( a ratio of polyethylene glycol to polylactic acid is 1 : 1 . 2 , and a drug - carrying capacity is 6 %) in embodiment 1 disclosed in cn201110105540 . 2 . the docetaxel nano - polymer micelle lyophilized preparation was prepared according to the embodiment 11 of the present invention , which was an experimental group , wherein three parallel experiments were performed for the experimental group , and were marked as embodiment 11 - 1 , embodiment 11 - 2 and embodiment 11 - 3 . physiological saline was added into the preparation of the control group and the experimental group respectively for dissolution until the concentration was 1 mg / ml ( by docetaxel ), and then placed under a room temperature ( 25 ± 2 ° c .) to detect the encapsulation efficiency thereof in different time . results were as shown in table 2 . the encapsulation efficiency of the micelle was measured using high speed centrifugation ( 10000 r / min , 10 min ), wherein the encapsulation efficiency =( 1 - free drug / total drug ) * 100 %. when determining the encapsulation efficiency of the docetaxel polymer micelle using hplc , chromatogram conditions used were as follows : ods was used as a filling material , 0 . 043mol / l ammonium acetate aqueous solution - acetonitrile ( 45 : 55 ) was used as a mobile phase , and a detection wavelength was 230 nm . theoretical plate number calculated by a docetaxel peak should not be less than 2000 . as shown in table 2 , the encapsulation efficiency of the drug in the experimental group was still greater than 90 % at 24 h , while burst release occurred to the drug in the control group at 0 . 5 h .