Combining　different　independent　cloud　services　must　coordinate　their　access　control　policies.　Otherwise　unauthorized　access　to　composite　cloud　service　can　occur　when　there＇s　a　conflict　among　different　cloud　service　providers＇　access　control　policies,　and　then　it　will　bring　serious　data　security　and　privacy　issues.　In　this　paper,　we　propose　Packet,　a　novel　access　control　policy　composition　method　that　can　detect　and　resolve　policy　conflicts　in　cloud　service　composition,　including　those　conflicts　related　to　privacyaware　purposes　and　conditions.　The　Packet　method　is　divided　into　four　steps.　First,　employing　a　unified　description,　heterogeneous　policies　are　transformed　into　a　unified　attributebased　format.　Second,　to　improve　the　conflict　detection　efficiency,　policy　conflicts　on　the　same　resource　can　be　eliminated　by　adopting　cosine　similarity-based　algorithm.　Third,　exploiting　a　hierarchical　structure　approach,　policy　conflicts　related　to　different　resources　or　privacy-aware　purposes　and　conditions　can　be　detected.　Fourth,　different　conflict　resolution　techniques　are　presented　based　on　the　corresponding　conflict　types.　We　have　successfully　implemented　the　Packet　method　in　Openstack　platform.　Comprehensive　experiments　have　been　conducted,　which　demonstrate　the　effectiveness　of　the　proposed　method　by　the　comparison　with　the　existing　XACML-based　system　at　conflict　detection　and　resolution　performance.