Based on the minimum potential energy principle and combining with the Ritz method, the theoretical model of single and multiple shim stacks were established respectively to calculate deformation value under the uniform load. ANSYS was used to establish the finite element model of valve deflection, and a comparison was made with the deformation of the analytic expression by any radius. The results show that the analysis formula of valve deformation is correct based on the energy method, and the analytical results are more accurate. The influence rules on the valve deformation stiffness of key parameters, such as the valve plate thickness, the valve plate outer radius, the retaining ring radius and the number of shim stacks, were further analyzed. The research shows that the valve deformation stiffness increases with the increase of the valve plate thickness, the retaining ring radius and the number of shim stacks, and decreases with the increase of the valve plate outer radius. The conclusions provide a certain theoretical guidance for parametric design of shock absorber.