Cloud　computing　provides　elastic,　scalable　on-demand　IT　services　for　individuals　and　organizations.　In　the　cloud　computing,　everything　is　as　the　service.　Cloud　clients　enjoy　convenience　and　efficiency　service,　but　at　the　same　time　encounter　new　issues.　Cloud　clients　needs　to　provide　authentication　information　to　access　to　service,　which　often　contains　a　lot　of　sensitive　information.　The　service　provided　by　Cloud　is　dynamic,　diverse,　and　context-related.　The　traditional　identity　authentication　methods　which　implement　coarse-grained　to　allow　or　prohibit　access　is　no　longer　to　adapt　service-oriented　cloud　computing.　In　this　paper,　we　propose　a　service-oriented　identity　authentication　privacy　protection　method.　In　the　method,　we　define　cloud　service　access　control　as　a　process　and　extending　the　cloud　client　related　information　into　a　fuzzy　set　as　the　authentication　condition　for　the　exchange,　according　to　the　amount　of　information　security　level,　dynamic　opening　the　corresponding　service　access　control　and　providing　fine-grained　service-oriented　identity　authentication,　guarantees　global　minimal　sensitive　information　disclosure,　and　maximally　protects　individual　privacy.