The　major　environmental　loads　of　mineral　separation　process　in　China　iron　production　(with　missing　data)　are　analyzed.　And　the　inner　relationship　between　these　loads　data　is　qualified　and　the　missing　data　are　imputed　using　a　statistic　method　called　Multiple　imputation　(MI),　aimed　to　improve　the　quality　of　LCA　datasets　and　allow　industry　to　easily　conduct　a　highly　reliable　LCA.　By　using　computer　simulation,　MI　replaces　each　missing　value　with　a　set　of　plausible　values　which　represent　the　uncertainty　of　the　missing　data.　The　multiply　imputed　datasets　are　then　analyzed　by　the　standard　procedures　for　completing　data　and　combining　the　results　from　these　analyses.　The　result　proves　that　MI　Method　is　an　effective　and　reasonable　method　to　solve　the　problem　of　missing　data　and　therefore　can　ensure　the　validity　and　reliability　of　LCA.