A 3D numerical model for tripod pile foundation and superstructure of an offshore wind turbine was established based on ANSYS finite element platform. The modal shapes and vibration characteristics of the FEM were determined through the modal analysis by using Block Lanzcos method. Considering the effect of periodic wave loads, the dynamic response characteristics of the FEM were respectively calculated through the transient analysis. Therefore, the time-history curves of displacement and stress in the key parts of the structure were obtained. The analysis results show that: the tripod pile foundation and superstructure of the offshore wind turbine were easy to show as the bending form, indicating the higher bending performance of the structure. Under wave loading, the time-history curves of displacement and stress showed a periodic oscillatory motion with the change of time, but there were also differences. As to the time-history curves of displacement, the far the key parts away from the foundation, the larger the displacement amplitude, and the more remarkable the nonlinear characteristics of the curves. As to the time-history curves of stress, the stress amplitude appeared at the top of the column, which is the connecting part between the column and the tower. The wave loads cannot be ignored, which have important influences on the stress state and deformation of the offshore wind turbine structure.