Abstract: In view of requirement in GB 3836.2－2010 standard that it must use Ni-Cd battery, lithium battery and Ni-MH battery as standby battery in standby power supply system of mine flameproof electrical equipments, a standby power supply system of flameproof electrical equipments based on Ni-MH battery was designed. Working principle of Ni-MH battery and design requirements of the system were analyzed, design of charging management unit and protection unit of the system were introduced in details, and test result of the system was given. The actual application shows that the system can meet requirement of GB 3836.2－2010 standard with stable running, safe and effective protecting measures.