In　the　traditional　Service-Oriented　Architecture　(SOA),　Web　service　providers　register　their　service　descriptions　in　the　registry　for　service　clients　to　perform　service　discovery　and　invocation.　Although　this　architecture　provides　loose　service　invocation,　it　lacks　a　dispute　resolution　mechanism　to　guarantee　the　trusted　service　invocation　between　untrustworthy　service　providers　and　clients.　Blockchain　technology　has　unparalleled　advantages　in　decentralization　and　tamper-resistance,　and　can　be　employed　in　the　SOA　to　solve　the　untrustworthiness　of　service　invocation.　Combining　the　SOA　architecture　and　blockchain　technology,　this　paper　proposes　a　blockchain-based　trust　framework　for　SOA,　where　the　blockchain　is　used　as　an　evidence　recorder　and　a　service　registration　proxy.　To　ensure　the　service　traceability,　each　service　invocation　is　signed　by　both　the　service　provider　and　client　involved　as　a　trusted　credential　on　the　blockchain.　The　trusted　credentials　on　the　blockchain　will　be　retrieved　for　verification　when　a　service　dispute　occurs.　Moreover,　the　input　parameters　and　results　of　a　service　are　encrypted　during　constructing　trusted　credentials　to　ensure　the　privacy　of　service　data.　The　experimental　results　show　that　the　proposed　framework　can　correctly　handle　the　service　disputes　between　service　providers　and　clients　in　the　case　of　all　independent　malicious　behaviors　and　most　of　the　combined　malicious　behaviors,　compared　with　traditional　methods.　It　also　could　realize　the　automatic　conversion　from　Web　services　to　trusted　services,　and　complete　the　trusted　service　invocation　within　2.5s.