Spray drying method: add the twelve trisodium phosphate crystallization water dissolving tank add l0 % ~ 15% of the water, heating to 85 ~ 95 ℃, stir to dissolve after solvent cleaning, the refined solution pumped to the metering tank, the spray atomization, choose two streaming airflow nozzle atomizer, the atomizing steam guide Angle and level is 30 ° and 0.15 ~ 0.3 Mpa atomizing steam pressure, inlet temperature of 650 ~ 750 ℃, the outlet temperature of 140 ~ 170 ℃ under the spray drying, anhydrous trisodium phosphate was finished.