To make the rotation of the rotor blade more accurate, the elastic deformation in the system is considered in this paper. Firstly, the number and direction of the generalized coordinates are determined by the freedom degree of the blade and the finite element method and Lagrange equation are used to build the dynamical equation of the rotor blade system. Then, the mass matrix and other coefficient matrix are obtained according to the principle of flexible multibody dynamics. Finally, the violation correction method is used to get the numerical solution of the dynamical equation in the simulation. Additionally, the angular displacement and the deformation of the blade end with in the y-direction and z-direction is analyzed to prove the correctness of the model.