Abstract: For coal mine demand of explosion-proof lithium ion battery, a kind of power supply circuit of explosion-proof lithium ion battery was designed, composition and functions of the circuit were introduced in details. The circuit uses flame-proof cavity design, when the lithium ion battery units or battery management system happen failure, the charging control system and discharging control system can quickly and reliably disconnect with the lithium ion battery, so as to ensure safety of other equipments. The circuit has functions of charge and discharge protection, voltage balance protection, over temperature protection and real-time display.