The floating foundation is designed to support a 1.5MW wind turbine in 30m water depth. Considering the viscous damping of foundation and heave plates, the amplitude-frequency responses characteristics of the foundation are studied. Taking the elastic effect of blades and tower, the classic quasi-steady blade-element/ momentum (BEM) theory is used to calculate the aerodynamic elastic loads. Coupled dynamic model of turbine-foundation-mooring lines is built to calculate the motion response of floating foundation under Kaimal wind spectrum and regular wave by using the FAST codes. The model experiment is carried out to test damping characteristics and natural motion behaviors of wind turbine system, as well as the motion responses considering joint of wind and wave and only with wave. It is shown that the wind turbine system can avoid the harmonic vibration by the wind and wave, in addition, the floating foundation heave is induced by wave, while surge motion is induced by wind, and the action of wind and wave is of significance for pitch.Copyright © 2014 by ASME