Abstract: In order to meet special requirements of backup power in coal mine refuge chamber, firstly serial lithium-ion batteries were put in an explosion protection box with their battery management system. Then parallel explosion protection boxes formed the backup power system. The system included voltage detection and bala nce controller, battery pack module controller, assembly controller, LCD controller. It collected voltage and temperature data by distribution voltage sampling method an d DS18B20 temperature sensor. It collected current data by current hall sensors. Then system took steps to prevent over voltage, over temperature, over current etc. Th rough field test verification, system operation was steady, measuring error of current and voltage were far less than the specified value of coal mine safety standards.