Abstract: This paper introduced the current situation of on-board data transmission and application of existing EMU, according to the application scenario of 5G technology, proposed the overall architecture of EMU on-board data transmission and monitoring system based on 5G technology, defined the functions of real-time monitoring of operation status, fault alarm correlation analysis and big data prediction analysis of the system, used the key technologies such as enhanced bandwidth, high reliability, low delay and network slicing to implement more accurate and comprehensive real-time monitoring of EMU, and provide guarantee for the operation safety of EMU.