A new method to eliminate the oil whip online is put forward by use of passive electromagnetic damper. The damper works contactless and with DC current. Neither sensor nor closed loop control is needed. The dynamic equations of rotor-bearing system are built up by combining d'Alemdert principle with Rize way, and the nonlinear oil film forces based on unsteady short bearing model are coupled to system. Such nonlinear equations are numerically solved by Newmark integration method. The calculated results show that the bifurcation behavior of the system can be changed and the oil whip of the rotor may be well damped by external damping. The bifurcation diagrams also show that the subharmonic vibration amplitude decreases in motion and the speed at which the system losses its stability increases obviously by exerting external damping.Then experiments are carried out to demonstrate this phenomenon. It is observed that the complex trajectories of the journal motion are disappeared and the rotor-bearing system became stable when the power of passive electromagnetic damper is turned on. The experiments have good repeatability.