Underground drilling and sealing tool and drainage construction method

The invention discloses an underground drilling and sealing tool, and relates to the technical field of coal mine gas extraction, the underground drilling and sealing tool comprises a drilling deviceand a grouting sleeve device. The drilling device comprises a guide reamer bit and a plurality of centralizers. Each centralizer comprises a centralizer body, a first drill rod and a second drill rod.One end of the guide reamer bit is in threaded connection with one end of the first drill rod. The grouting sleeve device comprises a first sleeve, a second sleeve, a guide shoe, a first flange plateand a first connecting pipe. The invention further discloses a drainage method adopting the tool. The construction method has the beneficial effects that the construction method is suitable for underground large-diameter drainage drilling hole forming, pipe descending and pipe fixing. By the adoption of the construction method, in the drilling process, the guide reamer bit drills, the centralizerstraightens the drilling tr