Abstract: Taking the new continuous production technology of  industrial monoammonium phosphate（MAP） by the purification of wet-process phosphoric acid as the background，with 20%（mass fraction） P2O5 wet-process phosphoric acid as raw material，barium salt as desulfurizing agent，potassium carbonate as defluorination agent，and silica as additive， one-time pretreatment was made for desulfurization and defluorination by chemical precipitation method.The rates of desulfurization and defluorination were 83% and 87.82%，respectively.Then industrial grade MAP was obtained by the ammonia neutralization for two times in a row，twice concentration in consecutive double-effect，and by continuous crystallization.The prepared industrial MAP′s chemical composition（mass fraction） was as follows：N（11.85%），P2O5 （59.62%），NH4H2PO4 （96.68%），F-（0.17%），and  SO42- （0.64%），which reached the requirements of Industrial Grade MAP Standard（GB 10205—2009）.

Key words: defluorination, desulfurization, industrial MAP