Abstract: In recent years,electrical fire monitoring systems have been set up in urban metros in response to the national fire prevention requirements. However,the application effect of the electrical fire monitoring system is not ideal,that there are frequent false alarms,caused by long-term sizable leakage currents in multiple circuits of the station power distribution system. Starting with the actual measurement data of the station,considering the power supply mode of each load and the internal power distribution mode of the equipment,the main causes of leakage current occurrence are analyzed and corresponding improvement measures are proposed,with the expectation to fundamentally solve the problem of sizable leakage current of the station power distribution system,ensuring safe,green and efficient operation of the metro electrical system.