In order to reveal the influence of different inclination angles of tip winglets on the efficiency of horizontal axis wind turbine blades, five kinds of tip winglets with different inclination angles were designed. The aerodynamic performance of tip winglets with different inclination angles was analyzed by the structured grid technique and the Computational Fluid Dynamics(CFD)method. Thereafter, the results by analyzing and comparing their aerodynamic performance show that the output power and rotor power coefficient of five kinds of wind turbines are all significantly improved with winglet, and the maximum output power increases by 16. 73%, while the rotor power coefficient increases by 4. 41%. Winglets with larger inclination angle can more increase pressure difference between the upper and lower airfoil section of the blade and the bend moment of the root of winglet is smaller. Besides, winglets with large inclination angle can significantly improve the tip flow around the blade, break up the strong vorticity dragged at the tip of blade, and reduce the loss of energy at the blade tip.