In this chapter, the vibration response characteristics of NREL’s 15 MW floating wind turbine under the environmental combination of wind shear incoming flow, turbulent wind, and regular and irregular wave conditions are investigated by numerical simulations with OpenFAST software. It is found that the wave load mainly affects the fore-aft shear at the base of the tower, where the irregular wave has the most significant effect on the response value; the turbulent wind significantly increases the volatility of the side-to-side shear at the base of the tower. The environmental contour method is used to predict the ultimate response of the unit, and the study shows that the wind turbine will show the ultimate response under specific conditions, which are as follows: under the conditions of wind speed of 10 m/s, significant wave height of 5.36 m, and spectral period of 11.61 s, the fore-aft shear at the tower base of the wind turbine will show the ultimate response; under the conditions of wind speed of 25 m/s, significant wave height of 3.95 m, and spectral period of 6.23 s, the side-to-side shear at the base of the tower will show the ultimate response. The side-to-side shear at the base of the tower shows the limit response for the case of wind speed 25 m/s and spectral period 6.23 s.