In　modern　gas　turbine　engines,　the　first　stage　vane　endwall　endures　high　thermal　load　with　the　increase　of　the　turbine　inlet　temperature　and　the　uniformity　of　the　temperature　distribution　at　combustor　outlet.　Moreover,　the　endwall　secondary　flow　forces　the　coolant　flow　toward　the　suction　side,　resulting　in　hot　regions　along　the　pressure　side　endwall.　In　the　worst　case,　hot　regions　lead　to　thermal　failure.　In　order　to　ensure　that　the　gas　turbine　operates　safely,　advanced　cooling　techniques　are　urgently　needed　to　be　implemented　to　reduce　the　hot　regions　along　the　pressure　side　endwall.　In　the　current　research,　the　influences　of　the　pressure　side　injection　slot　on　the　film　cooling　performance　of　the　endwall　surface　were　numerically　investigated.　The　three-dimensional　Reynolds-averaged　Navier-Stokes　(RANS)　equations　combined　with　the　shear　stress　transport　(SST)　k-omega　turbulence　model　were　solved　to　conduct　the　simulations.　Cases　with　different　injection　slot　configurations　have　been　simulated.　The　results　indicate　that　the　hot　region　along　the　pressure　side　endwall　is　significantly　reduced　by　introducing　the　pressure　side　injection　slot.　The　coolant　from　the　pressure　side　injection　slot　is　assisted　by　the　pressure　side　vertical　flow　toward　the　adjacent　vane　suction　side.　Therefore,　the　coolant　coverage　and　the　cooling　effectiveness　are　increased.　In　this　study,　the　expanded　slot　(ES)　achieves　a　larger　cooling　effectiveness　than　the　normal　slot　(NS)　and　convergent　slot　(CS)　at　a　small　blowing　ratio　M=0.5.　In　contrast,　the　CS　obtains　a　larger　cooling　effectiveness　than　the　NS　and　ES　atM=1.0　andM=1.5.　In　addition,　the　introduction　of　the　pressure　side　injection　slot　has　a　small　influence　on　the　aerodynamic　performance　of　the　vane　cascade.