Metaphase and late sanitary landfill leachate from Asuwei in Beijing was taken as the research object. By means of orthogonal experiments, the effects of dosage, stirring speed, stirring time and standing time of modified bentonite, natural bentonite, alum, and modified bentonite with alum on the CODcr elimination rate of landfill leachate were analyzed. After analyzing the mechanism of landfill leachate treatment by using natural bentonite, modified bentonite and alum, modified bentonite and natural bentonite were used to treat hydrophobic compounds and hydrophilic compounds of dissolved organic matter (DOM) in landfill leachate respectively, and alum was also used to flocculate landfill leachate. The CODcr and BOD5 values of the treated landfill leachate were much lower than values of the untreated landfill leachate, decreasing from 4700 mg/L to 839 mg/L and 700 mg/L to 263 mg/L, with the CODcr and BOD5 elimination rates of landfill leachate being 82.15％ and 62.43%, respectively. It is shown that the treatment of landfill leachate by combination of modified bentonite, alum and natural bentonite is an effective method.