Abstract: Due to extreme wind conditions such as strong turbulence and sudden wind direction change, which frequently lead to serious accidents, a calculation method of dynamic response for large-scale megawatt wind turbine suitable for various complex wind conditions is proposed in this paper. The blade element momentum theory (BEM), hybrid beam theory, finite element method, modified Newmark-β method and Lanczos decoupling technology are combined together, and the dynamics characteristic such as unsteady inflow effect of flexible rotor, shear deformation and centrifugal stiffness effect, aerodynamic- structural damping effect, structural coupling between flexible components as well as nonlinear large deformation are taken into consideration. The dynamics characteristic of megawatt wind turbine under ETM (Extreme turbulence model) and ECD (Extreme coherent gust with direction change) conditions are further analyzed. Some interesting phenomena are found as follows. The wind direction angle will cause the overshoot in loading effect, resulting in a large sudden change of displacement for blades and towers before they tend to be stable. The flapwise blade deformation is greatly affected by the extreme turbulence. The longitudinal turbulence component will lead to severe vibration of a tower in the fore-aft and side-to side directions. The research method is of great significance for the determination of wind turbine aeroelastic stability under extreme wind conditions and the realization of rigid flexible coupling dynamics simulation technology.