Abstract: Ferric sulfate was prepared at the first step by calcination and acidic leaching from iron stone.A new type of inorganic high molecular coagulant——polyferric silicate sulfate (PFSS) was prepared by using ferric sulfate and sodium silicate as raw materials.Preparation process conditions of PFSS as well as the effect of PFSS dosage and pH value of the wastewater on coagulative effect were studied.Results of coagulative experiment for treating wastewater showed that removing effect of COD,turbidity,and chroma of PFSS was much better than those of polyferric sulfate (PFS).Optimum preparative technological conditions of PFSS were as follows:mass fraction of SiO<SUB>2</SUB> was 3%,activation time of silicic acid was 40 min,pH of activation was 2,and amount-of-substance ratio of Fe to Si was 0.50.