Abstract: According to the serious air leakage of the gas drainage borehole in the mining seam, low drained gas content and short effective gas drainage period, t his paper analyzed the air leakage mechanism and key technology of borehole sealing of the gas drainage boreholes in the mining seam, provided the radial swelling a nd permeation sealing technology of the gas drainage borehole in the mining seam and stated the technical principle of the technology to seal the borehole with crack Z one around the borehole. Finally, combination with the cases, a rational borehole sealing depth of the gas drainage borehole for No. 2210 coal mining face in a mine wa s determined as 16 m. The experiment showed that with the application of the radial swelling and permeation sealing technology, the fraction of the gas drainage volum e was increased by 21% ~ 32%, the average gas drainage flow was increased by 0.016 m3/ min and the gas drainage period could be extended by 1 ~ 2 months. Thu s a safety and high efficient gas drainage could be ensured and the waste of the sealing material and the formation of the gas drainage blind zone could be avoided.