In　order　to　validate　the　service　of　cloud,　an　improved　remote　attestation　scheme　based　on　unbalanced　hash　tree　of　cloud　platform　was　proposed.　Double-layer　unbalanced　hash　tree　was　built　by　introducing　layer,　original　single　tree　was　expanded　to　main　tree　and　sub　tree,　which　corresponded　to　virtual　machine　in　cloud　platform　and　the　running　components　in　virtual　machine.　Attestation　needs　no　more　than　measurement　component　and　authentication　path.　The　analysis　shows　that　this　scheme　can　increase　the　attestation　efficiency　of　cloud　platform,　and　is　good　at　protecting　privacy　and　expandability,　which　is　suitable　for　validating　cloud　platform　service.　©　2017,　Editorial　Board　of　Journal　on　Communications.　All　right　reserved.