Inorganic polymer flocculants play an important role in water treatment. The copolymerization of Al3+ and Fe3+ in proportion can prepare polyferric aluminum (PFA), which can improve the flocculation performance of polyferric (PFe) on the premise of reducing Al3+ residue. The effects of Al/Fe and OH?/Fe on the micromorphology, physicochemical properties and flocculation performance of polyferric aluminum phosphatic sulfate (PFAPS) were studied in this work. The results show that Fe3+ and Al3+ form Fe-monomer and Al-monomer by combining with six oxygen atoms from H2O or anion. And then these monomers form polymers through the bridging of various anions. Although the binding mode is similar, XRD results show that pfaps and PFPS are amorphous. The flocculation performance of PFAPS first increases and then decreases with the increase of Al/Fe and OH-/Fe.