Abstract: In view of requirement of GB 3836.2-2010 that battery with precipitated combustible mixture cannot be used in flameproof shell, a start-up power supply system of lithium-ion battery of mine-used explosion-proof diesel locomotive was designed with serial lithium-ion batteries. Design requirements and structure of the system were analyzed, and design of battery management unit of the system was introduced in details. The battery management unit combines LTC6803 with microcontroller to realize voltage detection and equalization control of single battery, uses DS18B20 temperature sensor to collect temperature of single battery and employs double current hall sensors to collect start-up current and charging current of the batteries. The test results show that the system runs stably, and measuring errors of voltage and current are far less than specified value of coal mine safety standards.