The hydroxyl phosphate as a functional monomer was synthesized by GMA and phosphoric acid at a low temperature, followed copolymerization with acrylic monomers to prepare a styrene-acrylic emulsion. The modified styrene-acrylic emulsion were characterized by IR、SEM, Tafel and particle size analysis and the performance of its film was tested . The results showed, the waterborne anti-corrosion emulsion reaction system was stabile and the particle diameter of emulsion is about 100nm having relatively narrow distribution. When the dosage of hydroxyl phosphate was 4%，the coating was prepared by the emulsion with the best corrosion resistance and overall performance, without flash-rust resistant appearance. The corrosion current of the paint film was 1.376×10-8A, which is better than the commericial waterborne anti-corrosion coating film on the anti-corrosion properties.