The invention provides a method for
coal bed gas exploitation of a full working face through a down-hole
system. The method comprises the following steps that a plurality of vertical wells are dug in the positions, a preset distance away from a main roadway along the full working face, on the ground, and all the vertical wells penetrate through a
coal mine layer;
horizontal wells are dug, the horizontal well sections of the
horizontal wells are located in the
coal mine layer, and the left-right deviation distances, relative to the vertical wells, of the horizontal well sections are between 0.3 m and 0.6 m; after the ground
horizontal wells and the vertical wells are all completed, a down-hole horizontal well is dug in the main roadway along the coal mine layer, and the left-right deviation distance, relative to the vertical well nearest the main roadway, of the down-hole horizontal well is between 0.3 m and 0.6 m; a control
pipe line is mounted on a well mouth of the down-hole horizontal well; cavity expansion is conducted on coal mine layer sections allowing the vertical wells to penetrate through
reamer bits, and all the ground horizontal wells and the down-hole horizontal well communicate with all the vertical wells; and
coal gas exploitation of the down-hole full working face is conducted through the control
pipe line mounted on the well mouth of the down-hole horizontal well. According to the method for coal
bed gas exploitation of the full working face through the down-hole
system, the problem that pumping and drainage of the full working face cannot be achieved in the exploitation process of coal
bed gas is solved.