Abstract: The limit charging test of large capacity lithium-ion battery used in coal mine is carried out and internal pressure in flameproof enclosure is researched in case of the battery explosion or pressure release. The paper proposes the design of pressure relief device and anti-blocking structure, and the pressure relief effect is compared and verified by experiment. In the end, flameproof enclosure with pressure relief function for large capacity lithium-ion battery is developed and tested.