Abstract: The preparation method of high-quality ammonium dihydrogen phosphate (DAP) from wet-process phosphoric acid （mass fraction of P↓2O↓5=25.71％） with high impurity content after purified by methanol precipitation method was introduced in this paper.The effects of various factors，such as reaction temperature，reaction time，amounts of methanol and ammonium bicarbonate，on the removal of the impurities in wet-process phosphoric acid and on the loss ratio of P↓2O↓5 were discussed.The optimal process conditions were obtained as follows：the amount-of-substance ratio of ammonium bicarbonate to phosphoric acid is from 0.25 to 0.50，weight ratio of methanol to phosphoric acid is 4，reaction temperature is 65 ℃，the reaction time is from 1.25 to 1.50 h.High-quality DAP (specification：18-46-0) has been prepared from the purified phosphoric acid obtained under the above-mentioned optimal conditions.This new method provides a feasible route for producing high-quality fertilizer-DAP from medium and low grade phosphorite.