Abstract: Zhongxing Coal Mine was a gassy mine, and there was air leakage fissure in 1413 fully mechanized caving face of this mine, which made the fire source of the abandoned coal in goaf unable to be extinguished, and then caused the CO concentration in roadway to seriously exceed the limit, and it was very likely to lead to the occurrence of explosion accident. Therefore, in order to achieve the purpose of extinguishing fire source safely, in view of the coexistence of fire and gas, the technology of "solid, liquid and gas" three-phase combined explosion suppression and fire extinguishing was put forward. From the "blocking, isolation, extinguish" three points of view, the trinity explosion-proof walls with plugging, absorbing energy and absorbing heat were built around the fire source firstly; then the goaf was continuously injected with nitrogen to inert goaf environment to reduce the possibility of explosion; finally, the measures of blasting suppression and fire suppression were carried out by sealing the air leakage channel with jet grouting and cooling the high level borehole with high water-retaining gel by pressure injection. The practice results show that the CO concentration in goaf is restored to the normal level, fire in the area is quickly extinguished, and the temperature in the embedded hole is always below 25 ℃, which solves the problem that the fire source of the abandoned coal cannot be extinguished in gassy environment, and provides a guarantee for the safe production of coal mine.