Considering the aero-hydro-mooring-control coupled performance of a floating Vertical Axis Wind Turbine (VAWT), the numerical model of the floating helical VAWT system is established, and the fully coupled simulation program of the floating helical VAWT is developed. The aerodynamic load of the wind turbine system is calculated using the unsteady BEM model, and the hydrodynamic load is calculated using the 3D potential theory. The floating foundation is considered as a rigid body, and the blades and tower are considered as flexible bodies. Based on the Kane method of a multi-body system, the dynamic responses of the VAWT could be solved in the time domain. A variable speed control model considering efficiency and load is established to match the rotating speed with the wind speed, and it could maintain the target output power under the influence of turbulent wind and large-scale movement of the floating foundation. The control strategy of limiting the target speed change rate and low-pass filtering is adopted to ensure the rapid regulation of the wind turbine under low wind speed conditions and stable regulation under high wind speed conditions.