Abstract: Aiming at the problems of low concentration of borehole extraction, fast attenuation of borehole extraction concentration and flow rate caused by poor sealing effect in the process of gas extraction in the dynamic pressure roadway of Sangshuping No.2 mine, by studying the development depth of loose circle in adjacent air dynamic pressure roadway, detecting the leakage position of borehole in current sealing process, and analyzing the causes of borehole leakage, a precise sealing technology of borehole is proposed, which includes optimizing the reasonable sealing depth, sealing area and sealing mode of borehole.The technology is applied in gas extraction of dynamic pressure roadway.The results show that the leakage depth of borehole is within 15 m of borehole.The main causes of gas leakage are leakage in sealing section and surrounding rock fracture and deep gas leakage in string hole drilling.The development depth of loose circle is 5 m.Compared with the original technology, the gas concentration in borehole is more than 59% after using the precise sealing technology of borehole, which is about 3 times that of the original technology.