Abstract: The pitching motion of floating wind turbine platform with tension-leg is analyzed based on the fluid-impulse theory, and a feedback control strategy is proposed to apply the active damping to the pitch motion. The feedback control system is designed in the case of the electrical output is not affected. The 5 MW wind turbine with tension-leg platform provided by NREL was modeled using FAST software and is co-simulated with MATLAB/Simulink software. The simulation results show that the designed feedback control system can not only reduce the fore-aft displacement of the tower top, the fluctuation of the rotor speed and the electrical power output, but also reduce the tower base rolling moment to a certain extent by using the FAST and MATLAB/Simulink software and is helpful to improve the life of the tower.