Abstract: Aiming at the problems of low detection efficiency, low detection accuracy and high labor cost in the traditional detection methods for gas leakage of Electric Multiple Units(EMU), this paper designed an ultrasonic intelligent monitoring and identification system for compressed gas leakage of EMU. The system can accurately judge the sealing state of components and determine the location of compressed gas leakage by collecting and analyzing the ultrasonic signals generated by the leaked gas. The test proves that the designed system can quickly detect and identify small gas leakage in the complex acoustic environment of the maintenance site, accurately and effectively determine the leakage location of the faulty components of the EMU, significantly improve the detection accuracy and efficiency, and ensure the operation safety of the EMU.