Physical experiments were conducted in this study to investigate the flow velocity distribution and the turbulence characteristics in the wake of a horizontal axis tidal stream turbine under the combined action of wave and current. The results show that the existence of wave would contribute to the recovery of flow velocity behind the support structure. Compared with that under pure current, larger velocity deficit was observed within the swept area and slower velocity recovery rate was found in the far wake, when the model turbine operates under the combined action of wave and current. It’s also found that the flow velocity in the downstream of turbine would increase with the increasing of wave height and wave period. Meanwhile, turbulence intensity in the flow field under combined wave and current is generally higher than that under a pure current condition. In addition, turbulence intensity would decrease with the increasing of wave period, while would increase with the increasing of wave height.