Curtain grouting method is a mature technology applied to block up the underground water in tunneling. But it was applied to block up the high pressure gas what is very seldom. Driving the coal mine tunnel in fracture zone where having vast high pressure gas (CH4 and H2S) was research. On the basis of studying existing research achievements, the calculating method of Hydraulics safety thickness was applied to count the critical safety thickness. The technique combined the pipe roof technic and curtain grouting method and assured the tunneling safety. This research achievement was triumphantly applied tunneling at +450 wind road, Sichuan province Longtan coal mine.