Abstract: The direct evaporation method was applied to treat landfill leachates from early,middle and late ages in this paper.The effects of evaporation process on COD_Cr and NH₃-N volatilization were investigated.Result showed that the volatilization of COD_Cr and NH₃-N from landfill leachates were the highest in the early evaporation stage,significantly reduced in the middle evaporation stage,and slightly raised in the last evaporation stage.The volatilization of COD_Cr and NH₃-N were significantly effected by pH value.Low COD_Cr volatile content and much higher NH₃-N volatile contents of landfill leachate from middle and late ages were shown in the neutral and alkaline conditions.Less COD_Cr volatile content of landfill leachate from middle and late ages and much less NH₃-N volatile contents of landfill leachate from early and late ages were shown in the acidic condition.Both the COD_Cr concentration in the condensate liquid of landfill leachate from middle and late ages except from middle age in the acidic condition,and the concentration of NH₃-N in the condensate liquid of landfill leachate from early and late ages in the acidic condition are below Standard for Pollution Control on the Landfill Site of Municipal Solid Waste(GB16889—2008) special discharge limits.The COD_Cr and NH₃-N concentration in the condensate liquid of landfill leachate from the middle age achieved or was only slightly above the discharge limits of the Standard in the acidic condition.The volume of landfill leachate was reduced to 1 /6-1 /10 of theoriginal volume.The amount of subsequent treatment is significantly reduced.A valuable technique for application was provided to efficiently and economically treat landfill leachate with middle and late ages.