Abstract: The industrial monoammonium phosphate（(MAP） could be prepared through wet process phosphoric acid purifi- cation，as well the process route and conditions for the production were obtained.In the production of industrial products，the agricultural monoammonium phosphate was also by-produced.After wet phosphoric acid aging，desulfurization，defluorina- tion，neutralization，and separation，MAP supernatant liquor was obtained.Then through concentration，crystallization，separa- tion，and drying，the industrial monoammonium phosphate crystals were got.Finally，the crude MAP was obtained through mixing the filtered slag of neutralization liquor with the crystallization liquid.The prepared industrial MAP was in line with the above requirements of Class II product quality of Industrial Ammonium Dihydrogen Phosphate Standard，HG/T 4133—2010.This method had advantages of simple process，high quality，and low impurity，which could get better social and economic benefits.

Key words: wet process phosphoric acid（WPA）, phosphoric acid purification, industrial grade monoammonium phosphate