In order to study the influence of high tidal current velocity on the dynamic characteristics of horizontal axis tidal turbine under free wave conditions, STAR-CCM+ was used to establish a numerical calculation method for the hydrodynamic characteristics of tidal energy turbines under sea wave conditions. The law of wave influence on the rotation of tidal energy turbines and the characteristics of wake flow generated during the rotation were obtained. The results show that the amplitude and frequency of the angular acceleration of the tidal energy turbine are affected by the waves, but the fluctuation amplitude is less than the wave amplitude, the variation frequency is higher than the wave frequency. The wake flow produced by the rotation of the hydraulic turbine will make the flow field around the next hydraulic turbine more chaotic, and will have an impact on the blade rotation, turbine shaft load and energy utilization efficiency. Based on the analysis of the changing trend of pressure fluctuation, it is considered that the wake flow has little effect on the fatigue damage of hydraulic turbine.