Abstract: Based on CFD and finite element method, the aerodynamic characteristics and structural mechanical properties of the NREL 5 MW wind turbine composite blade under extreme operating gusts are studied by using Fluent and Transient Structural modules of ANSYS Workbench platform. The results show that aerodynamic loads of the wind turbines are greatly affected by the extreme operating gust. Under the extreme operating gust, the torque and axial thrust of the wind turbine have a large respond greatly with the change of wind speed, and the peak value of the response is earlier than that of the gust. The blade displacement with the change of wind speed appears two peaks before and after the peak of wind speed. When the wind speed reaches the peak, the surface stress of the blade increases greatly compared with that of the uniform-stream stage.