Based on the finite element method,the wave force mechanism on a platform structure of offshore wind turbine was analysed and the dynamic response and wave force variation on the platform structures were obtained in time domain.The wave force variations on platforms with different pile structure types in the directions of surge,sway and heave as well as of roll,pitch and yaw were investigated.The results show that for multi-pile structure platforms,the frequency changes only in an arrow band and the vibration mode has only a little change;in sway direction the wave force is minimum and in pitch direction the wave force is maximum.