Abstract: The change of wind direction significantly affects the aerodynamic load distribution of wind turbines and thus affects the stable and efficient operation of wind turbine and aerodynamic load is one of the main influencing factors of wind turbine structural stress and power variation. Taking the S-airfoil three-blade horizontal axis wind turbine designed by the research group as the research object, the wind tunnel test is carried out on the rotating platform. The stress of wind turbine blades and tower and the power characteristics of wind turbine are analyzed under different wind direction change speeds (0.5°/s, 1°/s, 1.5°/s, 2°/s). The results show that when the wind direction change speed is 0.5°/s, the chordwise and spanwise stress values of the blade and the wind turbine power drop the most when the wind direction changes from 0° to 30°; when the wind direction changes from 0° to 20°, the stress values of the blade and power decrease relatively slowly, and the stress and power of the wind turbine will further decrease after the wind direction change ends. The wind direction change angle is in the range of 0°~20°, the stress value of the tower fluctuates greatly which is affected by the coupling effect of the blade speed and the decreasing speed of aerodynamic load and the wind direction change, and with the increase of the wind direction change speed, the fluctuation range advances from 15°~20° to 0°~5°. After the wind direction change ends, the blade speed continues to decrease, the tower stress still fluctuates to varying degrees, and the results provide some theoretical basis for the structural design of wind turbines operating under wind direction change.