The invention belongs to the field of gas detection manufacturing industry and discloses a coal-body gas drainage method and device. An PCL controller is arranged on a machine frame, and a plurality of data connecting ports are arranged on the PCL controller; a gas concentration detector is in key connection with the outside of the machine body; a gas storage tank is arranged inside the machine body, and two ends of the gas storage tank are in expanded connection with conduits; a gas suction hood fixed outside the machine body is in expanded connection with a conduit; an air suction fan is fixed inside the machine body through bolts, and the air suction fan is in expanded connection with conduits; a gas pressure reducer is arranged between the conduits; a gas detection apparatus is fixed on the left side of a gas compression tank; the gas compression tank is arranged inside the machine body; an one-way valve is in key connection with the inside of the gas compression tank. The coal-body gas drainage device is simple in structure, the amount of gas emission can be increased, the strength of gas drainage is greatly improved, energy can be supplied directly after the gas is processed,inputs of other energy are reduced, and the drainage efficiency of coal seam gas can be integrally improved.