Polysilicate metal salt exhibits excellent flocculation ability. Polysilicate aluminum ferric(PSAF) was prepared through copolymerization by sulphates and chlorides of aluminum or iron with polysilicate acid. The optimal hydrolysis parameter of different PSAFs was determined. Differences in turbidity and flocculation function of four types of PSAFs were evaluated. Furthermore, differences in coagulation and phosphorus removal were analyzed and discussed.