Floating wind turbines are quite different from the inshore and onshore wind turbines. Especially their dynamic responses need more requirements of simulation for the complex floating motions. Floating wind turbines experience not only the air loads, but also the wave loads from the sea. A free vortex wake method is used to calculate the wind turbine aerodynamic loads. The wave motion is simulated based on the linear wave and the PM energy spectrum, and the Morison equations are used to calculate the wave loads. The structural dynamics equation for the tension leg platform is then solved to obtain the dynamic responses of the platform, in which the airloads and hydroloads are coupled and fed back to the aerodynamic calculation. For completeness, the aerodynamic and structural dynamic responses of a 1.5 MW wind turbine with the tension leg platform are simulated and the influence on the wind turbine aerodynamic characteristics of the platform motion is analyzed.