Abstract: In order to study the influence of the vibration and deformation of the blade on the aerodynamic damping of the horizontal axis wind turbine, the aerodynamic force is calculated using the BEM theory, and the dynamic response is calculated using finite element method, and then the aerodynamic damping model is built based on the energy loss method. The influence of flapwise, edgewise and twist deformation on the angle of attack is mainly studied. The influence of the flapwise velocity and edgewise velocity on inflow angle and inflow velocity is also taken into consideration. As an example, the aerodynamic damping of a 5 MW offshore baseline wind turbine rotor is calculated. The results indicate that the angle of twist and the flapwise deformations have great influence on the aerodynamic damping in flapwise direction. It may reduce the aerodynamic damping in flapwise direction, but the edgewise deformation only affect the aerodynamic damping in edgewise direction. The deformation has no influence on aerodynamic damping distribution alone the blade.