A NREL 5MW wind turbine was chosen as the research object, and the fluidstructure coupling numerical model of the wind turbine blade was established based on ANSYS Workbench platform. The variation laws of displacement and stress of the wind turbine blade with rotating speed were explored, and the data of the maximum displacement and stress of the wind turbine blade under different rotating speeds were fitted by using Fourier function. The results show that the displacement and stress response of the blade increase with the speed, and the peak values move to the left, the period increases in the same amount of time, and the peak value increases but the increase amplitude decreases; with the increase of rotating speed, the displacement shows an distribution increased from the blade root to the tip, while the maximum stress of the blade concentrates in the middle and the root. The curves of the maximum stress and displacement of the blade with the change of rotating speed present Sshape, and the Fourier fitting curve well reflects the response law of the blade. The results provide reference for the safe operation of wind turbines.