A new type of inorganic coagulant, solid-liquid oxidative poly silicic ferric sulfate (PSF-I), was prepared by adding KMnO4 and stabilizer M to poly silicic ferric sulfate (PSF). The species characteristics of PSF-I, the filtrate of PSF-I and PSF with spectrophotometer, and coagulation performance of PSF-I and the filtrate of PSF-I with jar tests were explored, respectively. Coagulation efficiency of PSF-I was studied compared to that of PSF and poly ferric sulfate (PFS), and the effect of storage time on coagulation performance of PSF-I was investigated. The results show that KMnO4 added to PSF modifies the microstructure of PSF, increasing species size of PSF and making UVA characteristic peaks of Fe3+ ion in PSF-I higher than that in PSF. There exists KMnO4 unattached in PSF-I. The solid phase in PSF-I is a kind of primary nucleus for building up flocs. The optimal dosage with PSF-I is 9 mg x L(-1), in comparison with 12 mg x L(-1) by PSF-I filtrate. The removal of natural organic matters (NOM) is not only caused by adsorption/charge-neutralization and co-precipitation but also by oxidization using PSF-I as coagulant, while to PSF and PFS, adsorption/charge-neutralization and co-precipitation is the only coagulation mechanism.