Leachate sludge was solidified by using sulphoaluminate cement（SAC） and municipal solid waste incineration fly ash as cementitious materials. The composite curing effect and curing mechanism of cement and fly ash were explored through an unconfined compressive strength test， leaching toxicity analysis and microscopic test. The results show that when the cement content is not less than 20%， 28 d unconfined compressive strength of the cement solidified sample meets the landfill strength requirements. Fly ash is an excellent auxiliary curing agent for cement solidified leachate sludge， and its enhancement effect on the unconfined compressive strength of cement solidified samples has an optimal dosage. 10% fly ash can replace 10% cement to achieve a better curing effect. The samples with 30% or 40% cement + 15% fly ash can meet the requirements of landfill strength and leaching toxicity at the same time.