Abstract: In view of the problem that gas leakage is caused by fracture connection of coal and rock around gas extraction borehole and failure of sealing material, which leads the concentration and net flow of gas extracted from borehole decreases greatly and the expected target of extraction can't be achieved, this paper analyzes the main causes of air leakage in borehole and puts forward a universal repair technology for failure borehole.That is, through numerical simulation analysis, the junction position of the stress increase zone and the stress zone of the original rock is obtained, and the annular slot is constructed here, supplemented by the "sealing two sections and grouting in the middle" with pressure grouting sealing technology, to repair the failure borehole.The field test results show that after the failure hole is repaired, the average gas extraction concentration increases by more than 3 times, the average gas extraction net flow increases by more than 50%, and the service life of the borehole is effectively prolonged.