Abstract: The gas fluctuates frequently in the old goaf 2313 of Geting Coal Mine, and the harmful gas leaks out continuously. Through the gas analysis, gas pressure observations and tracer gas leakage detection, the influence factors of gas change in goaf are determined. During the formulation and implementation of goaf closed air leakage blocking measures, the "nitrogen pressure equalization chamber" has been established, and the inorganic plastic material is used to fill the closed fractures around, which improves the air tightness of goaf, and keep the inerting state of goaf.