Abstract: Through analyzing the mechanism of borehole leakage and sealing, it was pointed out that there were mainly 3 types (type a, type b and type c) of gas leakage points in gas drainage borehole. Among them, type c, namely coal composite fracture, was the main type of gas leakage in current drainage boreholes. In order to improve the pre-drainage effect of gas in No. 16 coal seam of Feitian Coal Mine, the experiment of efficient borehole sealing and quality improvement technology was carried out in 11161 transport roadway. Based on the measurement of the axial distribution law of methane volume fraction in the sealed borehole, it was analyzed that there was mainly type c gas leakage in the borehole, and the reasonable sealing depth of the test site was determined to be 15 m, and the comparative test of borehole sealing were carried out. During the inspection period of about 70 days, compared with the polyurethane sealing process in the same drainage period, the average volume fraction of methane extracted from the test borehole increased, the range for increasing was from 30% to 40%, and no obvious attenuation occurred. The results show that the efficient sealing technology can effectively overcome the type c leakage in drainage boreholes and has excellent engineering application value.