To improve the power production of offshore wind farms, a combined wind turbine and wave energy converters concept is proposed in the present work. This concept is composed of a semi-submersible floating horizontal axis wind turbine and four torus-shaped wave energy converters. The relative heave motion between the tori and the columns on the semi-submersible platform is used to harvest wave energy. A coupled model of this combined concept is established by integrating the aerodynamic loads on blades, hydrodynamic loads on the platform with moorings and the wave energy converters and controller of the wind turbine. Coupled time-domain simulations are carried out to predict the power performance and dynamic responses of this combined concept under various conditions with turbulent wind and irregular waves. The results indicate that the introduced wave energy converters can obviously contribute to the annual power production of the combined concept when compared with an individual floating wind turbine. Moreover, the combined concept has benign dynamic responses under different environmental conditions and plays a positive synergy in improving power production.