The topological structure of a metro train network control system was introduced, and the design of MVB communication parameters and communication quality evaluation criteria was expounded. Aiming at two typical MVB communication faults occurred in a metro train network control system, after eliminating the influence of physical lines, external electromagnetic interference, software and hardware design of subsystems and other factors, by means of MVB analyzer and oscilloscope to locate the cause of failure, the problem of communication failure was solved by adjusting the relevant parameters of the underlying software communication of MVB board in train network control system. Finally, aiming at the similar problems of rail transit vehicles, the fault investigation and analysis methods were provided for reference.