Abstract: Based on the common failures of train communication network, train communication network on-site detection method is summarized. For on-site detection, the test practicality on items such as frame-to-frame error, process data, frame interval, signal amplitude, signal rising edge time and distur-bance is higher. The main treatment process and test results of train communication network on-site failure disposal cases are sorted. The train communication network failure modes and the general steps of troubleshooting train communication network failures are summarized.