The stability of platform structure is the most basic guarantee for safety operation of offshore wind turbines.A whole machine model was built based on the ITI energy barge platform to research the time-domain dynamic response and frequency-domain performance under certain wind,wave and current conditions.Dynamic responses of the platform structure were analyzed under the time-varying conditions of structure amplitude and wave frequency.The contribution of F-K force and diffraction force to the structure with six degrees of freedom movement as well as the changing tendency of the wave force along with the change of frequency were analysed.The results show that the response amplitude operator(RAO) of platform and the wave force acting on platform are prone to get large under low frequency wave action.The structural responses in the heave,surge and pitch directions are obvious than those in the other three directions.