Abstract: In view of the temperature rise fault of traction motor bearing of certain type of EMU (electric multiple unit), investigation is carried out from the aspects including bearing structure, grease injection amount and frequency, influence of shaft voltage, pulsating torque check to find out the cause of bearing damage and the consequent faults. Analysis results show that under the continuous action of weak current, high temperature operation of bearing and other factors, the aging of lubricating grease is accelerated, resulting in poor lubrication of bearing. In serious cases, white corrosion fractures appear on the bearing, and finally lead to bearing fatigue failure. According to the fault causes, measures such as optimizing lubrication, increasing the thickness of insulation layer and increasing protective grounding are proposed.