Spontaneous　condensation　flows　are　highly　non-equilibrium　processes,　which　has　strong　coupling　with　the　gas　flow　field　in　the　two-phase　condensing　flow.　The　development　of　accurate　multi-phase　numerical　model　is　necessary　to　reveal　the　mechanism　of　the　non-equilibrium　condensation　flow.　The　gas-liquid　inter-phase　slip　not　only　has　great　influence　on　the　gas　flow　and　the　motion　trajectory　of　condensing　droplet,　but　also　would　affect　the　condensation　process.　A　multi-fluid　condensing　model　is　presented　for　the　multi-component　condensing　system,　of　which　the　gas-liquid　inter-phase　velocity　slip　and　the　temperature　difference　is　taken　into　account.　The　model　is　used　for　the　numerical　analysis　of　the　wet　steam　condensing　flow　in　supersonic　nozzle.　The　simulation　results　showed　that,　the　inter-phase　velocity　slip　has　significant　effects　in　the　two-phase　wet　steam　flow,　and　the　proposed　multi-fluid　model　which　takes　the　inter-phase　slip　into　account　can　improve　the　simulation　accuracy.　In　the　wet　steam　flow,　the　inter-phase　slip　and　temperature　difference　are　very　significant　at　the　initial　stages　of　condensation,　and　then　the　non-equilibrium　properties　almost　disappear　until　the　near　equilibrium　state　is　reached.　©2014　Journal　of　Mechanical　Engineering