Abstract: Through the experimental tests,the dynamic rotating platform is used to simulate the wind direction change and the yaw motion of the wind turbine. The effects of different yaw speed and yaw delay time on blade stress and power were studied. The results show that In the process of dynamic yaw motion,the stress value decreases gradually from the leading edge to the trailing edge of the blade and from the blade root to the tip. The stress concentration occurs at 0.67R and 0.75R in blade spanwise direction,0.25c and 0.5c in chord direction of blade root. The yaw delay time can effectively suppress the blade stress fluctuation. Too slow yaw speed will lead to large fluctuation of power curve. The dimensionless coefficient is introduced,which is the ratio of power and blade stress. Through analysis,it is known that when only the stress and power of wind turbine blade are considered,the optimal yaw speed of wind turbine is0.5°/s.