Drill gas drainage effect mainly depended on the quality of sealing borehole, pressurized sealing technology can improve the drainage borehole sealing quality and gas drainage effect. But, in the field application process, sealing grout leakage caused drilling scrapped. Through the test, the author found the causes of sealing cement slurry leakage, put forward the "five sections four tubes three steps" borehole sealing method, gave the main technical parameters of hole sealing, solved pressurized sealing grout leakage for borehole in coal seam roof, improved the drainage borehole sealing quality, extraction concentration and net amount, achieved with pressure sealing and improved the extraction effect. Through comparing the two adjacent drill field experiment, single hole drainage concentration increased an average of 2.5 times, time unit drainage net amount increased 1.8 ~ 2.2 times.