Abstract: To analyze the dynamic characteristics of the hydropower plant and solve the position of the stiffness center, based on the traditional calculation method of the stiffness center, the method of obtaining the flexibility coefficient in the calculation formula is changed, and the calculation method of the stiffness center of the hydropower plant is revised. By taking the powerhouse of a hydropower station as the calculation model, this paper carries out the rigid-flexible coupling simulation analysis by using the finite element software ANSYS, and the stiffness center of the structure is obtained. In addition, the factors affecting the accuracy of the calculation results are analyzed when ANSYS is used to solve the stiffness center. The results show that the revised stiffness center calculation method combined with ANSYS software can solve the stiffness center of complex structure, the solution speed and accuracy are also higher than the traditional calculation method. However, in the solution process, the uneven refinement of the grid will cause the lateral stiffness of the calculation model to change unevenly, which has a certain influence on the accuracy of the numerical calculation results of the stiffness center.