Lean　burn　premix　technology　of　gas　turbines　results　in　that　the　turbine　combustor　outlet　has　strong　swirl　flow　characteristics　which　directly　influences　the　inlet　flow　condition　of　the　first　turbine　vane　downstream　from　combustor　and　raise　the　thermal　load　of　endwall.　The　aerothermal　performance　and　film　cooling　effectiveness　of　first　turbine　vane　endwall　at　different　inlet　swirl　conditions　is　numerically　investigated　in　this　paper.　The　flow　pattern,　Nusselt　number　distribution　and　film　cooling　effectiveness　of　turbine　vane　endwall　at　the　uniform　and　three　kinds　of　swirl　numbers　(0.6,　0.8,　1.0)　inflow　conditions　with　clockwise　and　anticlockwise　swirl　orientations　are　analyzed　using　three-dimensional　Reynolds-Averaged　Navier-Stokes　(RANS)　and　SST　k　-　turbulence　model　solutions.　The　obtained　results　show　that　the　flow　field　is　apparently　influenced　by　inlet　swirl　conditions.　The　separation　in　passage　is　clearly　suppressed　at　clockwise　swirl　inflow　conditions　but　anticlockwise　make　the　flow　pattern　more　complex.　Inlet　swirl　can　increase　the　overall　Nu　on　the　endwall.　Especially　in　the　area　upstream　of　leading　edge　and　area　between　the　first　and　second　row　of　film　holes　whose　Nu　are　increased　by　4　and　1.5　times　compared　with　uniform　inflow,　respectively.　Not　only　swirl　number　but　also　orientation　can　affect　the　film　cooling　effectiveness　distribution　of　the　vane　endwall.　The　better　film　cooling　effectiveness　distribution　and　higher　film　cooling　effectiveness　downstream　of　each　film　hole　row　can　be　achieved　at　the　clockwise　swirl　inflow　conditions　by　weakening　the　accumulation　of　coolant　near　the　suction　side　of　the　turbine　vane　endwall.　Compared　with　uniform　inflow,　average　film　cooling　effectiveness　of　endwall　between　the　second　row　and　third　row　is　increased　from　0.21　to　0.27　at　clockwise　SN=1.0　for　the　maximum　increase.　The　detailed　flow　field　and　aerothermal　performance　of　the　turbine　vane　endwall　at　different　swirl　inflow　conditions　is　also　discussed　and　illustrated.　©　2021　by　ASME.