Abstract: 〗An optimization design model for blades of horizontal axis wind turbines has been presented in this paper, which takes the maximum of annual energy output as the design objective. And the probability of wind speed distribution has been taken into account. The PROPID program is used to get the baseline of blade with a better performance firstly, and then the genetic algorithm is used to optimize the baseline. In order to get a smooth blade figuration, a 5th order Bezier curve is used to fit through the control points. Using the developed optimization method, the blades of a 600kW wind turbine were designed. Compared with the initial blades, the designed shows obvious advantages, which verifies the effectiveness of the optimization method.