Since it is difficult to consider the actual working conditions of the leaf spring in its traditional design calculation method, the nonlinear factors of large deformation, contact and friction between the interleaf and gasket in actual working conditions are considered. The stiffness and strength characteristics of a leaf spring with variable stiffness for the rear suspension of a vehicle are analyzed using the finite element method (FEM). The results show that the accuracy of the established finite element model in which the nonlinear factors are considered is relatively high. On the basis of the accurate validation of the finite element model, the dynamic response of the leaf spring under harmonic load excitation is solved by using the transient dynamic analysis method. The dynamic characteristics of the leaf spring are obtained when the excitation load frequency and amplitude vary. The proposed modeling method can effectively simulate actual working conditions and provide a premise for further structural optimization of the leaf spring.