Abstract: In response to the lack of real-time transmission and application of on-board data for the Jakarta-Bandung high speed-railway which was not conducive to the diagnosis and analysis of Electric Multiple Units (EMUs), this paper was based on the working principle of the KCIC400AFEMUs onboard wireless transmission device, designed an on-board data real-time transmission architecture. The paper adopted key technologies such as wireless transmission security mechanism between vehicle and ground, real-time processing of distributed big data, and hierarchical multi-dimensional monitoring to implement on-board data real-time transmission for EMUs, meet the requirements of safety and reliability; Based on the repair business scenarios of EMUs, the paper analyzed the application of on-board data in real-time monitoring and fault handling, parameter correlation and operation and maintenance decision-making, and improved the operational safety guarantee capability of the Jakarta-Bandung high speed-railway.