Based on the characteristics of landfill leachate pollution, the coagulation performance and microstructure morphology of poly-ferric(Ⅲ)-magnesium(Ⅱ)(PFM)were studied. The results show that, under consistent experimental conditions, the PFM has better coagulation performance in dealing with landfill leachate compared with other inorganic coagulants. The removal rates of COD and chroma exceeded 60% and 80%, respectively, when the PFM was used. The PFM can fully display the superiorities of the iron component and the magnesium component in coagulation. The XRD and FTIR analyses show that the PFM is a kind of macromolecular composite polymer of iron and magnesium based on hydroxyl bonding.