Abstract: The intense interference of stray current is detected on the gas pipelines near a metro train depot. After repeated site tests and monitoring data analysis, the design defects of the unidirectional conduction device for depot entrance/exit lines are identified. According to the characteristics of the leakage current path and the rail insulation joints on entrance/exit lines, the hardware reform and software upgrade for the original system equipment are carried out, in order to realize the two\|way isolation and conduction control between the main line and the depot, so as to control the leakage current path within the scope of industry standards.