Taking　the　special　airfoil　of　S809　wind　turbine　as　the　object,　the　influence　of　the　triangular　flap　of　the　wind　turbine　trailing　edge　on　the　aerodynamic　performance　of　the　wind　turbine　blade　airfoil　is　studied　by　numerical　simulation.　The　Box-Behnken　response　surface　method　(RSM)　is　used　to　optimize　the　parameters　flap　height　H,　flap　width　D　and　flap　deflection　angle　θ　of　the　triangular　flaps.　The　quadratic　regression　analysis　is　applied　to　obtain　the　response　relationship　between　the　trailing　edge　triangular　flaps　and　the　lift-drag　ratio　of　the　wind　turbine　blade.　The　optimal　combination　of　design　parameters　of　delta　flaps　is　determined.　The　results　show　that　H　has　the　greatest　influence　on　the　lift-drag　ratio　of　airfoil,　followed　by　θ　and　D.　Compared　with　the　original　airfoil,　the　lift　and　lift-drag　ratio　of　the　optimal　delta　flap　airfoil　determined　by　the　RSM　method　have　been　greatly　improved.　In　addition,　a　Gurney　flap　with　the　same　height　and　width　as　the　optimal　triangular　flap　is　added　to　the　airfoil.　Numerical　simulation　results　show　that　the　flow　field　and　pressure　distribution　in　the　vicinity　of　the　Gurney　flap　are　basically　the　same　as　those　of　the　triangular　flap.　The　aerodynamic　performance　characteristics　of　the　model　have　the　same　trend　of　improvement,　but　the　aerodynamic　performance　of　the　additional　triangular　flaps　is　better.　©　2022,　Science　Press.　All　right　reserved.