It is necessary and fitting to use flexible multibody dynamics method to study the wind turbine blades. Because the characteristics of the blades will directly affect the whole wind turbine’s, and the results by using flexible multibody method are to agree with reality. Considering the anisotropic composite blades, it established the flexible blades model and rigid-flexible wind rotor model of the 750KW wind turbine by the software of ANSYS and ADAMS. Then fit the loads which are computed from BLADE to the wind rotor, analyze the dynamic characteristics of the rotor. It gets the dynamic features of the flexible blades and the rigid blades’ as a comparison, which will be useful to research on WTGS, and will supply reference data to blade trouble analysis and optimization design.