Abstract: To calculate the stiffness and damping between ball and inner/outer race under the status of elasto-hydrodynamic lubrication (EHL) contact on the surface, the dynamic differential equations of stiffness-damping were established. The system equations were numerically integrated to obtain the results of bifurcation diagram, phase diagram, Poincaré diagram and orbits plots. The effects of radial clearance and rotational speed on the dynamic behaviors were analyzed. The results show that both radial clearance and rotational speed are important factors for the nonlinear dynamic characteristics of the system. The rotor-ball bearing system with dynamic stiffness-damping property displays more complex dynamic characteristics.