The　use　of　security　certificates　under　the　Cloud　environment　is　the　foundation　to　establish　mutual　trust　between　the　Cloud　and　the　user.　In　this　paper,　we　propose　an　authentication　method　based　on　zero-knowledge　proof　and　the　mind　of　key　escrow.　With　the　method,　authentication　will　not　only　satisfy　the　requirement　anonymity　and　security　but　also　can　recover　the　real　identity　information　in　special　circumstances　with　the　cooperation　of　multiple　parties.　We　will　show　that　this　proposed　method　is　more　suitable　for　promotion　through　analysis　and　comparison　with　an　existing　scheme.　©　2015　SERSC.