Phosphogypsum is a solid waste produced by the phosphoric acid industry. With the development of the phosphoric acid industry, the emissions of phosphogypsum are increasing year by year and its recycling rate is low. The environmental problems caused by tailings storage are becoming increasingly serious. The chemical formula of the main component of phosphogypsum is . its performance is similar to that of natural gypsum. Using phosphogypsum as a raw material to produce phosphorus building gypsum is one of the main ways to utilize phosphogypsum resources. However, phosphogypsum building materials have poor water resistance and low strength, which greatly limits their application. Based on the analysis of the poor resistance mechanism of phosphogypsum, this paper analyzed and studied the mechanical and water resistance properties of phosphorus building gypsum by separately adding different amounts of polyvinyl alcohol and silane emulsion and mixing polyvinyl alcohol and silane emulsion . The conclusion is that adding waterproofing agents and water-reducing agents can greatly improve the water resistance of phosphogypsum building materials.