The invention discloses a gas extraction drilling vertical type pneumatic intelligent slagging water drainer and a using method thereof. The water drainer comprises an air inlet pipe intelligent control valve, an air cylinder, a pneumatic motor, a water drainer shell, a sealing transmission device and a support. One end of the air inlet pipe intelligent control valve is connected with a down-holeair supply pipe, the other end of the air inlet pipe intelligent control valve is connected with the air cylinder and the pneumatic motor, the sealing transmission device is installed inside the waterdrainer shell and is connected with the pneumatic motor, and the support is installed at the bottom of the water drainer shell. The water drainer is mainly applied to underground coal mine discharging of gas extraction drilling pipeline accumulated slags and draining of gas extraction drilling pipeline accumulated water. The using method of the water drainer comprises the steps of firstly determining the water draining time interval of the water drainer, setting the accumulated slag water storage and draining time through the air inlet pipe intelligent control valve, and connecting the waterdrainer with a roadway air supply pipe and an extraction pipeline separately. The water drainer is novel in design, due to the structural innovation, intelligent and efficient slagging and water draining of the gas extraction pipeline are achieved, and the problems that a traditional water drainer is likely to be blocked and the slagging and water draining efficiency is low are solved.