Most cars belong to independent suspension vehicle and their front shafts are broken, for which their steering system are more complex than non-independent suspension vehicle. The reason of the front wheels occur to oscillate is not evident which keeps shimmy control from going. It is a severe problem that needed to be solved urgently because it can lead to the tires bursting and lose manipulation stability. Therefore, many nonlinear factors and mechanism elasticity were taken into account synthetically during modeling, including clearance of steering mechanism, elasticity and clearance of redirector, nonlinear lateral force of tire, dry friction of the pin. Based on the second Lagrange method, 4-DOF high dimension nonlinear vibration model was established. Numerical analysis presented the influence rules of nonlinear parameters, structural parameters and positional parameters to vibration characteristics of the steering system, and open out the vibration specialty of the system and mutual influence relation of system parameters. The results could give the theoretical and technical support for dynamic design and mutual matching of structural parameters, and shimmy control. 