Abstract: Landfill leachate, whose main pollutants are organic matter, heavy metals and ammoniacal nitrogen, is a kind of poisonous, harmful and organic wastewater. The pretreatment of landfill leachate by flocculation-adsorption was investigated. Polyaluminium chloride (PAC) was used as the flocculant and its optimum dosage was 500 mg/L. The adsorbent was self-made modified bentonite. Experimental results showed that approximately 79% of COD_cr and 46% of ammoniacal nitrogen were removed. As to heavy metals, the removal ratios were from 53% to 98% according to different kinds of landfill leachate.