Abstract: Polymeric ferric silicate sulfate containing boron (PFSSB) is a highly effective inorganic polymeric coagulant studied and prepared recently. The components' interactions of PFSSB were studied by chemical analysis and X ray diffraction in this paper, and the variations of pH and electrical conductivity with aging time were also investigated and analyzed. It is found that some interactions exist among Fe 3+ and its hydro polymer products, polysilicic acid, B and SO 2- 4 . These interactions of components play an important role in enhancing stability and coagulating properties of PFSSB.