With　the　development　of　economy,　China　has　become　one　of　the　largest　cement　producers　in　the　world.　However,　cement　industry　is　a　main　contributor　of　global　carbon　emissions.　Substituting　calcium　carbide　sludge　for　limestone　is　an　effective　method　for　CO2　emission　reduction　in　cement　industry　and　has　developed　rapidly　in　recent　years　in　China.　The　purpose　of　this　study　is　to　determine　the　life　cycle　CO2　emission　of　cement　clinker　produced　with　calcium　carbide　sludge　as　secondary　raw　material.　The　results　show　that　compared　with　general　cement　clinker,　the　life　cycle　CO2　emission　intensity　of　cement　clinker　produced　with　calcium　carbide　sludge　will　be　decreased　by　39.1%　when　substitution　rate　is　80%.　And　the　CO2　emission　results　from　the　procedure　of　cement　clinker　production　accounts　for　85.7%　of　the　total　emission,　in　this　stage,　the　CO2　emission　declined　by　42.2%.