the invention is described in detail in combination with the following specific embodiments , but the invention is not limited to the listed embodiments . explosives are prepared by taking 9 . 8 kg of an emulsion base , injecting 0 . 32 kg of a sensitizing solution , then adding 3 . 43 kg of polystyrene foam particles with the average particle size of 2 mm and the bulk density of 0 . 07 g / cm 3 and uniformly mixing . the density is determined to be 0 . 30 g / cm 3 , and the detonation velocity is tested to be 1502 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by taking 10 kg of an emulsion base , injecting 0 . 1 kg of a sensitizing solution , uniformly mixing , adding 0 . 01 kg of expanded perlite particles with the average particle size of 5 mm and the bulk density of 0 . 3 g / cm 3 and uniformly mixing . the density is determined to be 1 . 25 g / cm 3 , and the detonation velocity is tested to be 4993 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t 13228 - 1991 . explosives are prepared by taking 10 . 2 kg of an emulsion base , injecting 0 . 3 kg of a sensitizing solution , adding 1 kg of rice husks with the average particle size of 3 mm and the bulk density of 0 . 1 g / cm 3 and uniformly mixing . the density is determined to be 0 . 53 g / cm 3 , and the detonation velocity is tested to be 2702 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by the following steps : ( 1 ) taking 10 kg of an emulsion base , and injecting 0 . 1 kg of a sensitizing solution and uniformly mixing ; then ( 2 ) taking 4 . 5 kg of porous granular ammonium nitrate and 0 . 26 kg of diesel , and uniformly mixing ; ( 3 ) uniformly mixing mixtures prepared by the step ( 1 ) and the step ( 2 ); and ( 4 ) adding 0 . 0145 kg of polypropylene foam particles with the average particle size of 2 . 5 mm and the bulk density of 0 . 08 g / cm 3 into the mixture prepared in the step ( 3 ), and uniformly mixing . the density is determined to be 1 . 25 g / cm 3 , and the detonation velocity is tested to be 5003 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by the following steps : ( 1 ) taking 9 . 8 kg of an emulsion base , and injecting 0 . 32 kg of a sensitizing solution and uniformly mixing ; ( 2 ) taking 1 kg of porous granular ammonium nitrate and 0 . 058 kg of diesel , and uniformly mixing ; ( 3 ) uniformly mixing mixtures prepared by the step ( 1 ) and the step ( 2 ); and ( 4 ) adding 3 . 78 kg of a mixture of polystyrene foam particles with the average particle size of 2 mm and the bulk density of 0 . 1 g / cm 3 and expanded perlite particles ( wherein the mixture contains 1 kg of polystyrene foam particles and 2 . 78 kg of expanded perlite particles ) into the mixture prepared in the step ( 3 ), and uniformly mixing . the density is determined to be 0 . 3 g / cm 3 , and the detonation velocity is tested to be 1508 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by the following steps : ( 1 ) taking 10 . 2 kg of an emulsion base , and injecting 0 . 3 kg of a sensitizing solution and uniformly mixing ; ( 2 ) taking 3 kg of porous granular ammonium nitrate and 0 . 174 kg of diesel , and uniformly mixing ; ( 3 ) uniformly mixing mixtures prepared by the step ( 1 ) and the step ( 2 ); and ( 4 ) adding 2 kg of expanded perlite particles with the particle size of 5 . 0 mm and the bulk density of 0 . 3 g / cm 3 into the mixture prepared in the step ( 3 ), and uniformly mixing . the density is determined to be 0 . 73 g / cm 3 , and the detonation velocity is tested to be 3402 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by taking 10 kg of an emulsion base with negative oxygen balance , injecting 0 . 1 kg of a sensitizing solution and uniformly mixing ; then adding 4 . 5 kg of porous granular ammonium nitrate , uniformly mixing , finally adding 5 kg of polyethylene foam particles with the average particle size of 4 . 5 mm and the bulk density of 0 . 25 g / cm 3 , uniformly mixing and sensitizing . the density is determined to be 0 . 52g / cm 3 , and the detonation velocity is tested to be 2613 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by taking 9 . 8 kg of an emulsion base with negative oxygen balance , injecting 0 . 20 kg of a sensitizing solution and uniformly mixing ; then adding 1 kg of porous granular ammonium nitrate , and uniformly mixing ; finally adding 1 . 5 kg of a mixture of polypropylene , polystyrene and polyethylene foam particles with the average particle size of 4 mm and the bulk density of 0 . 20 g / cm 3 ( wherein the mixture contains 0 . 5 kg of polypropylene , 0 . 5 kg of polystyrene and 0 . 5 kg of polyethylene ), uniformly mixing and sensitizing . the density is determined to be 0 . 68 g / cm 3 , and the detonation velocity is tested to be 2946 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . explosives are prepared by taking 10 . 2 kg of an emulsion base with negative oxygen balance , injecting 0 . 32 kg of a sensitizing solution and uniformly mixing ; then adding 3 kg of porous granular ammonium nitrate , and uniformly mixing ; and finally adding 0 . 01 kg of expanded perlite particles with the average particle size of 0 . 5 mm and the bulk density of 0 . 03 g / cm 3 , uniformly mixing and sensitizing . the density is determined to be 1 . 20 g / cm 3 , and the detonation velocity is tested to be 4308 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . the emulsion base with the negative oxygen balance in embodiments 4 - 6 is prepared by adopting the following method : uniformly mixing 85 kg of ammonium nitrate , 0 . 122 kg of thiourea and 14 . 1 kg of water at the temperature of 80 ° c ., and regulating the ph value to 3 . 5 by using sodium hydroxide and acetic acid , wherein the crystallization point is 70 ° c ., and the turbidity of a solution is 0 . 8 ntu , as measured ; adding a diatomite adsorbent into the solution , and performing suction filtration by a coarse filter and a fine filter for 30 min in total to obtain a pure oxidizer salt water solution for later use ; melting and uniformly mixing 1 . 8 kg of lz2820 polyisobutylene succinic anhydride emulsifier and 5 kg of paraffin oil at the temperature of 70 ° c . to prepare an oil phase for later use ; and emulsifying the obtained oxidizer salt water solution and the oil phase in an emulsifier at the temperature of 80 ° c . to form a water - in - oil type emulsion explosive base . the viscosity is determined to be 15 bu . the emulsion base in embodiments 1 - 3 and 7 - 9 is prepared by adopting the following method : uniformly mixing 79 . 9 kg of ammonium nitrate , 0 . 122 kg of thiourea and 14 . 1 kg of water at the temperature of 80 ° c ., and regulating the ph value to 3 . 5 by using sodium hydroxide and acetic acid , wherein the crystallization point is determined to be 70 ° c ., and the turbidity of a solution is 0 . 8 ntu ; adding a diatomite adsorbent into the solution , and performing suction filtration by a coarse filter and a fine filter for 30 min in total to obtain a pure oxidizer salt water solution for later use ; melting and uniformly mixing 1 . 8 kg of lz2820 polyisobutylene succinic anhydride emulsifier and 6 . 22 kg of paraffin oil at the temperature of 70 ° c . to prepare an oil phase for later use ; and emulsifying the obtained oxidizer salt water solution and the oil phase in an emulsifier at the temperature of 80 ° c . to form a water - in - oil type emulsion explosive base . the viscosity is determined to be 15 bu . the sensitizing solution in embodiments 4 - 9 is prepared by adopting the following method : preparing the sensitizing solution by 0 . 09 kg of sodium nitrite , 0 . 09 kg of sodium bicarbonate and 2 . 62 kg of water . the invention further relates to the emulsion explosives with the different densities and the heavy emulsion explosives with the different densities , prepared by the methods described in the above embodiments . porous granular ammonium nitrate fuel oil explosives are prepared by taking 9 . 35 kg of porous granular ammonium nitrate and 0 . 65 kg of diesel , uniformly mixing , then adding 0 . 01 kg of expanded perlite particles with the particle size of 0 . 5 mm and the bulk density of 0 . 03 g / cm 3 into a mixture of the porous granular ammonium nitrate and the diesel , and uniformly mixing . the density is determined to be 0 . 9 g / cm 3 , and the detonation velocity of the explosives in the embodiment is tested to be 3302 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . porous granular ammonium nitrate fuel oil explosives are prepared by taking 9 . 55 kg of porous granular ammonium nitrate , 0 . 45 kg of diesel and 3 . 5 kg of polystyrene foam particles with the particle size of 2 . 3 mm and the bulk density of 0 . 12 g / cm 3 . the density is determined to be 0 . 30 g / cm 3 , and the detonation velocity of the explosives in the embodiment is tested to be 1633 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . porous granular ammonium nitrate fuel oil explosives are prepared by taking 9 . 45 kg of porous granular ammonium nitrate and 0 . 55 kg of diesel , uniformly mixing , then adding 1 . 5 kg of rice husks with the particle size of 5 mm and the bulk density of 0 . 3 g / cm 3 into a mixture of the porous granular ammonium nitrate and the diesel , and uniformly mixing . the density is determined to be 0 . 71 g / cm 3 , and the detonation velocity of the explosives in the embodiment is tested to be 3306 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . heavy ammonium nitrate fuel oil explosives of the embodiment are prepared by the following steps : ( al ) taking 9 . 55 kg of porous granular ammonium nitrate , 0 . 45 kg of diesel and 0 . 0109 kg of polyethylene foam particles with the particle size of 5 mm and the bulk density of 0 . 3 / cm 3 and uniformly mixing ; ( b1 ) uniformly mixing 4 . 8 kg of emulsion base and 0 . 15 kg of sensitizing solution ; and ( c1 ) uniformly mixing mixtures obtained in the step ( a1 ) and the step ( b1 ), then loading into a blast hole and sensitizing at the temperature of 0 ° c . for 20 min . the density is determined to be 1 . 25 g / cm 3 , and the detonation velocity is tested to be 4489 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . heavy ammonium nitrate fuel oil explosives of the embodiment are prepared by the following steps : ( a3 ) taking 9 . 45 kg of porous granular ammonium nitrate , 0 . 55 kg of diesel and 1 . 95 kg of polypropylene foam particles with the particle size of 3 mm and the bulk density of 0 . 12 / cm 3 and uniformly mixing ; ( b3 ) uniformly mixing 3 kg of emulsion base and 0 . 084 kg of sensitizing solution ; and ( c3 ) uniformly mixing mixtures obtained in the step ( a3 ) and the step ( b3 ). the density is determined to be 0 . 5 g / cm 3 , and the detonation velocity is tested to be 2608 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . heavy ammonium nitrate fuel oil explosives of the embodiment are prepared by the following steps : ( a4 ) taking 9 . 45 kg of porous granular ammonium nitrate and 0 . 55 kg of diesel and uniformly mixing ; ( b4 ) uniformly mixing 4 . 8 kg of emulsion base and 0 . 048 kg of sensitizing solution ; and ( c4 ) uniformly mixing mixtures prepared in the step ( a4 ) and the step ( b4 ) and 5 . 25 kg of expanded perlite particles with the particle size of 2 . 5 mm and the bulk density of 0 . 10 g / cm 3 . the density is determined to be 0 . 3 g / cm 3 , and the detonation velocity is tested to be 1633 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . heavy ammonium nitrate fuel oil explosives of the embodiment are prepared by the following steps : ( a5 ) taking 9 . 35 kg of porous granular ammonium nitrate and 4 kg of emulsion base with negative oxygen balance , and uniformly mixing ; ( b5 ) adding 0 . 075 kg of sensitizing solution and 4 . 67 kg of foam particles of a polypropylene - polystyrene - polyethylene mixture ( the mixture contains 1 . 5 kg of polypropylene , 1 . 67 kg of polystyrene and 1 . 5 kg of polyethylene ) with the particle size of 3 mm and the bulk density of 0 . 12 / cm 3 into a mixture obtained in the step ( a5 ) and uniformly mixing . the density is determined to be 0 . 35 g / cm 3 , and the detonation velocity is tested to be 1805 m / s according to a method for measuring a detonation velocity of an industrial explosive of gb / t13228 - 1991 . the emulsion base with the negative oxygen balance in the embodiment is prepared by adopting the following method : uniformly mixing 79 . 9 kg of ammonium nitrate , 0 . 122 kg of thiourea and 14 . 1 kg of water at the temperature of 80 ° c ., and regulating the ph value to 3 . 5 by using sodium hydroxide and acetic acid , wherein the crystallization point is determined to be 70 ° c ., and the turbidity of a solution is 0 . 8 ntu ; adding a diatomite adsorbent into the solution , and performing suction filtration by a coarse filter and a fine filter for 30 min in total to obtain a pure oxidizer salt water solution for later use ; melting and uniformly mixing 1 . 8 kg of lz2820 polyisobutylene succinic anhydride emulsifier and 6 . 22 kg of paraffin oil at the temperature of 70 ° c . to prepare an oil phase for later use ; and emulsifying the obtained oxidizer salt water solution and the oil phase in an emulsifier at the temperature of 80 ° c . to form a water - in - oil type emulsion explosive base . the viscosity is determined to be 15 bu . the negative oxygen balance in the embodiment means that oxygen contained in the emulsion base is insufficient to completely oxidize combustible elements . the emulsion base in embodiments 13 - 15 is prepared by adopting the following method : uniformly mixing 85 kg of ammonium nitrate , 0 . 122 kg of thiourea and 14 . 1 kg of water at the temperature of 80 ° c ., and regulating the ph value to 3 . 5 by using sodium hydroxide and acetic acid , wherein the crystallization point is determined to be 70 ° c ., and the turbidity of a solution is 0 . 79 ntu ; adding a diatomite adsorbent into the solution , and performing suction filtration by a coarse filter and a fine filter for 30 min in total to become a pure oxidizer salt water solution for later use ; melting and uniformly mixing 1 . 8 kg of lz2820 polyisobutylene succinic anhydride emulsifier and 5 kg of paraffin oil at the temperature of 70 ° c . to prepare an oil phase for later use ; and emulsifying the obtained oxidizer salt water solution and the oil phase in an emulsifier at the temperature of 80 ° c . to form a water - in - oil type emulsion explosive base . the viscosity is determined to be 16 bu . the sensitizing solution in embodiments 4 - 7 is prepared by adopting the following method : preparing 0 . 09 kg of sodium nitrite , 0 . 09 kg of sodium bicarbonate and 2 . 62 kg of water into the sensitizing solution . the invention further relates to the porous granular ammonium nitrate fuel oil explosives and the heavy ammonium nitrate fuel oil explosives with the different densities , prepared by the above embodiments .