Abstract: According to the gas accumulation in the roof fall of the gateway and the gas explosion problem might be occurred, took Tashan Mine as a study object, a physical model of gas content variation was established to analyze the gas content variation within the roof fall and the surrounding area under different air velocity a nd when an air guide plate was set up.The results showed that when the air velocity was 14 m/s, the air velocity increased could effectively reduce the local gas accum ulation in the roof fall and especially could effectively reduce the gas accumulated content of the fully falling roof (not over the roof falling depth of Terjier Theory) .Unde r a low air velocity, the gas would be accumulated within the roof fall, when the gas content was in an explosion delta scope, would be overlaid with the space-time of th e coal spontaneous combustion occurred and could cause a gas explosion disaster.Under a low air velocity, the air guided plate set could effectively discharge the gas accumulated in the roof fall, but the gas content at the downstream would increase. Based on the above analysis, the roof fall at 700 m of the air returning gateway in N 0.5208 coal mining face of Tashan Mine was determined to have a backfill operation.When the backfill operation completed, a thermal storage monitoring and measurin g was conducted on the area.An air guided plate was vertically set in the roof fall at 380 m of the gateway and the monitoring and measuring was conducted on the vari ation of gas content in the downstream air.