Abstract: The hole sealing depth directly affects the gas drainage efficiency of the whole system, its reasonable sealing depth is the key to ensure efficient extraction. Taking the through beds holes in floor drainge roadway as the research object, the fracture range in the surrounding rock of the drilling field was detected and analyzed by numerical simulation and the ultrasonic detection. The distribution of stress concentration zone was detected by velocity analysis of the drilling process. The gas drainage tests based on different sealing depth reveal that the shortest sealing depth is 10 m, which should exceed the boundary of the stress concentration zone.