Field plot experiment was carried to study the effect of applying the different amounts of desulfurized gypsum，as well as the desulfurization gypsum combined wtih polymaleic anhydride (HPMA) on alkali soil improvement in rice field.The results showed that the application of desulfurization gypsum decreased soil pH and alkalinity significantly.The biggest drop value of pH in topsoil was 1.59 and alkalinity (ESP) declined by more than 30%.The application of desulfurization gypsum affected the content of soil water soluble Na+，Ca2+，SO2-4，HCO-3 and then regulated the salt content of the soil.Appropriate application of desulfurization gypsum significantly reduced salt content of soil，which was 1.81 g·kg-1 for the largest decline，but the influence was opposite for excessive application of desulfurization gypsum.The desulfurization gypsum combined with polymaleic anhydride didnt decrease soil pH and alkalinity significantly，however reduced the salt content of the soil in some degree.The desulfurization gypsum combined with low amount of polymaleic anhydride significantly improved the soil alkali hydrolyzable nitrogen，available phosphorus and available potassium.