The structure of the low-voltage power supply network of the auxiliary system of the energy storage modern tram of Guangzhou Haizhu line was introduced, the power supply principle of the two vehicles coupled and the control logic of different power supply train lines were analyzed, and the fault conditions of the battery under voltage and single charger were described. The practical application of the product proved that the design of the power supply network was reasonable and the operation was stable, which could meet the use requirements of the energy storage modern tram.