Rubber bushing is an important connection component in vehicle suspensions. It plays an important role in vehicle performance. In the past years, the theories of rubber have been studied, and several forms of the strain energy potential, incompressible or almost incompressible, have been developed. But not all of these models are suitable for all kinds of applications. Therefore, when investigating the rubber bushing, it is necessary to find the effective constitutive equations.Two bushings with different shapes are studied. One is an ax-symmetric uniform bushing. The other one has additional two longitudinal holes. A process of parameter identification is conducted. The axial stiffness and radial stiffness of the bushing are tested and used as objectives. The parameters of constitutive equations are defined as design variables. The nonlinear analysis software ABAQUS and a multi-disciplinary optimization software OPTIMUS are used. The Latin-hypercube design and the self-adaptive evolution method are employed to find optimum parameters, which minimize the error of the simulated stiffness comparing to the test data. Other stiffness curves are then simulated and compared to the test data for evaluating the effectiveness of the constitutive models.The results show that it is feasible to identify rubber parameters with different constitutive equations for these two types of bushings. The constitutive equations can satisfy engineering application when the rubber deformation is small or medium. For rotational stiffness around the central axis, when the deformation is medium or large, the stiffness calculated with all constitutive equations seems higher than the tested one.