Abstract: The comprehensive utilization of phosphogypsum has the great significance for environmental protection and resource recycling.The impurities，such as phosphorus pentoxide，fluorine and organic matters in the phosphogypsum affect its application. In order to get high-quality phosphogypsum，the influences of reaction conditions，such as mass fraction of sulfuric acid，reaction temperature，reaction time and the ratio of liquid to solid etc.of leaching phosphogypsum by sulfuric acid on the content of acid-insoluble phosphorus pentoxide of phosphogypsum have been studied.Through single factor analysis and orthogonal experimental design，the optimal process conditions have been confirmed， which are as follows：mass fraction of sulfuric acid was 35%；reaction temperature was 60 ℃；liquid-solid ratio was 3∶1；reaction time was 4.5 h.Under these conditions P2O5 content down to below 0.01%.