a method of manufacturing oriented si steel containing cu with high electric - magnetic property comprises : hot rolling slab ; after first cold rolling , heating it to 800 ° c . or higher temperature and performing intermediate decarburization annealing in a protective atmosphere with p h2o / p h2 of 0 . 50 ˜ 0 . 88 for 3 - 8 minutes , to decrease carbon content of the steel plate to less than 30 ppm ; then peening and acid - pickling to remove oxide of fe on surface and to control oxygen content to lower than 500 ppm ; secondary cold rolling to final thickness and coating separation agent in water - slurry form ; drying to decrease water content to lower than 1 . 5 %; high - temperature annealing in a protective atmosphere containing hydrogen with oxidation degree of 0 . 0001 - 0 . 2 ; finally applying a tension coating and leveling tension annealing .