Abstract: The reasonable sealing depth of gas drainage drilling borehole plays a vital role in the coal seam gas drainage.For the shortcomings that the current mine generally use experience to determine the hole depth of the bedding gas extraction hole,the numerical simulation,the cuttings and the sealing mass spectrometer were used to study the length of the stress zone in the roadway.Furthermore,the reasonable sealing depth of bedding drilling was determined,and it was applied in Tucheng coal mine 21126 working face.The results showed that the reasonable sealing depth of the 21126 working face in Tucheng coal mine was 20 m,and the average gas extraction time in 3 months of the newly implemented drilling group was 2.21 times of that of the original mine drainage drilling group.It significantly improved the extraction efficiency of bedding drilling.