Abstract: In order to study the mechanism of coal spontaneous combustion in goaf which caused gas explosion, it proposed that the goaf was three-dimensional space formed by the oxygen concentration field, temperature field, air leakage intensity field and gas migration field which were in dynamic changing and coupling condition, and theoretically analyzed the danger coupling region and the mechanism of explosion. The results indicated that the danger coupling area became bigger because of high temperature and flammable gas caused by coal spontaneous combustion. The high temperature and flammable gas had the rising-diffusion effect, it undergone convective heat exchange with falling rocks and entrained the surrounding gas in the rising process, and further exchanged heat in the roof with rocks and formed the mixed gas of high concentration with CH₄. The temperature decreased, the density of mixed gas increased relatively，the mixed gas continued to accumulate and gradually led the lower to move down, while fire pressure effect formed the negative pressure zone in the wind inlet side, the eddy current effect produced entrainment effect and accelerated the gas mixed down, when the lower concentration and temperature of mixed gas reached the explosive limits then caused explosion. Finally it analyzed the effect of gas content for coal spontaneous combustion, and put forward the control technology of spontaneous combustion detonating gas for the high gas content and the low gas content goaf respectively, which included colloids and three-phase foam.