Abstract: According to the hydraulic accumulators used by explosion-proof vehicles in underground coal mines at present, the accumulators or pipelines are often removed with pressure during maintenance, resulting in high pressure oil gushing out, which is easy to form production safety accidents. In this paper, based on the characteristics of the explosion-proof vehicle engine work and the request of Coal Mine Safety Regulation, a set of accumulator automatic unloading device is designed. By detecting the oil pressure of engine, the oil pressure in the accumulator is automatically established or released to ensure that the oil pressure in the accumulator is automatically unloaded when the vehicle shuts down, avoiding the hidden danger of accidents caused by the operation with pressure. Through actual installation and test, it is proved that the automatic unloading system has small leakage, short unloading time and reliability.