The　sealing　efficiency　of　turbine　rim　radial　seal　is　numerically　investigated　by　3-D　Reynolds-averaged　Navier-Stokes　(RANS)　equations　and　SST　turbulence　model,　and　the　additional　passive　tracer　method　is　used　to　simulate　the　mainstream　ingestion　phenomenon.　The　rim　seal　experimented　in　Bath　university　is　selected　as　the　calculation　objective　to　verify　the　numerical　accuracy,　and　the　predicted　distribution　of　pressure　in　blade　passage　and　sealing　efficiency　of　the　rim　seal　at　different　cooling　flow　rates　well　agree　with　the　experimental　data.　The　influence　of　geometry　parameter　on　sealing　effectiveness　of　turbine　radial　rim　seal　is　numerically　investigated.　The　numerical　results　show　that　sealing　efficiency　of　the　rim　seal　increases　with　increasing　inner　fin　length;　the　sealing　efficiency　of　rim　seal　increases　with　decreasing　radial　clearance;　the　rim　seal　set　with　inner　fin　set　on　rotor　disk　has　the　higher　efficiency　than　that　on　stator　disk.　With　the　same　axial　and　radial　parameters,　upwind　fin　structure　can　improve　the　sealing　performance　of　the　radial　rim　seal.