The transfer path analysis （TPA） of the abnormal vibration guides to a two-level TPA model of a closing door's glass-the lock， weather-strip and glass at the first level and the rail junction and glass at the second. Based on the model， the operating load and path contribution， which determine the causes of the abnormal vibration， derive from the response of the testing points when the door is closed at 1.5 m/s（the speed at normal situations）. An improved scheme considering the reasons reduce the abnormal vibration of the door glass．