Abstract: The EMU is a high-speed vehicle for railway passenger transport, its operation and maintenance is an important part of railway transport, and its maintenance quality is directly related to the safety of passengers' lives and property and the economic benefits of enterprises. At present, various types of EMUs assigned to Lanzhou Bureau company have different degrees of abnormal odometer function, which has a great impact on the preparation of maintenance plan. This paper focuses on the full understanding of the working principle of the on-board odometer of EMU, and obtains a portable high-speed EMU odometer automatic calibration device with the 51 single chip microcomputer, which realizes the efficient calibration of the abnormal odometer, ensures the accuracy of the maintenance plan of EMU, and effectively prevents the delayed repair of EMU.