For an accurate analysis of the influence of yaw angle on the aerodynamic characteristics of the NREL Phase VI horizontal axis wind turbine (HAWT), the three-dimensional unsteady computational fluid dynamics (CFD) method in sliding grid technique is used in the simulation. In a case of 7 m/s flow velocity and 0° yaw angle, a comparison of the aerodynamic power and pressure coefficient is carried out between the CFD result and the experiment result, which validates our method. On the basis of this method, at the same flow velocity, different yaw angles are chosen to research the impacts of yaw angle on the aerodynamic characteristics of an HAWT. Meanwhile, the change of rules of aerodynamic power and 3D flow at different azimuthal angles are studied. Furthermore, the influence of different yaw angles on the sensitivity of unsteady aerodynamics is investigated.