NREL S809 airfoil was selected as an object to study the impact of trailing edge angle on its aerodynamic performances.The simulation results were compared with the experiment ones to rule out the grid quality effects on aerodynamic performance, the effectiveness of S-A (Spalart-Allmaras) turbulence model was verified and a reasonable simulation scheme was made sure to analyze the airfoil well and truly.On this basis, the S809 trailing edge swing angle was altered to generate S809 -5°, 5°, 10°, 15° deformed airfoils.Then the CFD software was used to analyze numerically each airfoil's aerodynamic characteristics.With the increase of trailing edge swing angle, the differential pressure on the upper and lower surfaces of the airfoil becomes bigger.So for the positive swing angle airfoils the lift and resistance characteristics are improved, however, when the airfoil swing angle is increased, the angle of attack becomes smaller and the separation vortex would appear.For negative swing angle airfoils, all of the lift, resistance and stalling characteristics are worse.