To　evaluate　the　effects　of　endwall　misalignment　and　axisymmetric　endwall　contouring　on　the　endwall　heat　transfer　characteristics　in　the　realistic　transonic　gas　turbine　cascade,　the　guide　cascade　in　the　first　stage　of　an　industry　gas　turbine　was　taken　as　the　research　object.　The　commercial　CFD　software　ANSYS　Fluent　15.0　was　adopted　to　numerically　investigate　the　endwall　flow　and　heat　transfer　characteristics　for　three　types　of　endwall　configurations,　including:　the　simplified　flat　endwall,　the　realistic　cascade　outer　endwall　(vane　shroud)　and　inner　endwall　(vane　hub)　with　axisymmetric　convergent　endwall　contouring　in　axial　direction,　at　the　gas　turbine　design　condition　(inlet　turbulence　intensity　of　16%,　exit　Mach　number　of　0.85).　The　endwall　thermal　load　distribution,　secondary　flow　field　near　endwall　and　backward　step　vortices　development　were　illustrated　and　compared　for　three　endwall　configurations　with　two　combustor-turbine　platform　misalignment　structures　(inlet　endwall　step　height　of　0,　6.78mm).　Results　showed　that　compared　with　the　flat　endwall　configuration,　the　axisymmetric　convergent　endwall　contouring　and　upstream　endwall　misalignment　can　result　in　dramatical　changes　in　the　endwall　secondary　flow　pattern　and　thermal　load　distribution.　In　general,　the　axisymmetric　convergent　endwall　contouring　can　result　in　a　relative　reduction　in　the　endwall　thermal　load,　especially　for　regions　of　endwall　juction　around　the　vane　leading　edge　and　downstream　the　vane　throat,　where　thermal　corrosions　were　more　likely　caused　due　to　the　poor　cooling　film　coverage.　In　real　gas　turbine　engines,　the　combustor-turbine　endwall　misalignment　can　dramatically　enlarge　the　high　thermal　load　region　(upstream　the　cascade　leading　edge)　which　was　migrating　to　the　downstream　cascade　passage,　and　result　in　a　significant　increase　(up　to　140%)　in　the　heat　transfer　level.　Therefore,　the　important　influences　of　the　endwall　contouring　and　endwall　misalignment　should　be　carefully　taken　into　account　for　the　endwall　cooling　scheme　design　of　the　first　stage　guide　cascade　in　the　real　gas　turbine　engines.　©　2019,　Editorial　Department　of　Journal　of　Aerospace　Power.　All　right　reserved.