Abstract: Based on the theory of gas flow in borehole, a quality testing device for borehole sealing was developed and manufactured. The gas leakage position was judged by gas concentration and negative pressure detection at different depth of borehole, which provides basis for sealing holes in gas extraction drilling. At the same time, using this device to choose two boreholes in Wangpo Coal Mine as the investigation object, the field test of the hole sealing quality detection was carried out, and the leakage point of the borehole was found. The test results showed that the device can accurately judge the sealing quality of gas drainage boreholes, which can effectively guide borehole sealing and improve gas drainage efficiency.