A new inorganic polymer coagulant，ploy-high-ferric-silicic coagulant with various Si/FeO42- ratios and salt-basicity, was prepared using the fly ash extract and potassium ferrate. The influence of both Si/FeO42- ratios and salt-basicity on the complexation process was explored with many analytical methods, such as transmission electron microscope (TEM), lased particle size analysis (LPSA) and infrared spectrum (IR). The results show that the ploy-high-ferric-silicic is a complexation compound, instead of a simple mixture of raw materials. The complexation process between Si and Fe may be different from various Si/FeO42- ratios and salt-basicity. The bonding can help revealing the high-ferric groups function in synthesis process. From analyzing the different ferrosilicon bonding modes, it can provide some theoretical basis to compound high-ferric coagulant.