This　paper　analyzes　the　principles　and　security　problems　of　delegation　mechanism　in　the　V1.2　specification　of　TPM,　and　proposes　a　new　delegation　scheme.　In　this　scheme,　a　merkle　hash　tree　(MHT)　has　been　maintained,　each　leaf　of　which　records　a　hash　of　a　delegation　blob　and　the　root　resides　in　TPM.　Based　on　the　MHT,　the　protocols　of　delegation　mechanism　were　improved.　The　MHT　has　been　updated　synchronously　in　the　creation　and　revocation　protocol　and　been　queried　to　judge　whether　the　delegation　blob　is　valid　currently　in　execution　protocol.　The　results　indicate　that　the　new　delegation　mechanism　is　feasible　and　the　reliability　and　security　of　delegation　model　have　been　improved　by　means　of　this　new　scheme.