Abstract: To solve the technical problem of low concentration and rapid attenuation of drilling in floor gas drainage gateway of Mengjin Coal Mine, we analyze the distribution of the fracture zone in the surrounding rock of the borehole, make clear the channel that may leak when the borehole is drained, and determine the length and position of the sealing section through the engineering test; according to the in-situ measurement of the extraction concentration of different parts of the borehole drainage pipe and the ground test, the leakage link of the drainage pipe was analyzed, and the connecting mode of the drainage pipe through the borehole was determined; in terms of sealing hole grouting, based on the analysis of drilling hole sealing technological process, the expansion rate of the final set of slurry was analyzed from water-cement ratio of 1∶2, and the improved sealing hole was obtained through the ground and field tests. The whole process of hole sealing technology is integrated. The results show that the concentration of borehole extraction can be increased to more than 2 times of the original by using the technology of straight through pipe and joint sealing.