Abstract: The vibration of a flywheel rotor with rotor/stop rubbing was investigated experimentally.The large amplitude of the rotor vibration was excited by the electromagnetic harmonic excitation force and thus caused the rubbing between the rotor and the stop.The rubbing force and its effects on the rotor were analyzed.The partial rubbing rotor vibration indicated that the inner type stop can limit the amplitude of asynchronous precession effectively.During the partial rubbing,the rotor/stop collision and rubbing appear occasionally.The partial rubbing has little effect on the rotating speed of the rotor.The partial rubbing will expand to full rubbing as the amplitude of the excitation becomes great enough.During the full rubbing,the rotor keeps contact with the stop and whips in a high frequency.The continuous friction makes rotating speed of the rotor drop sharply.