Abstract: In order to solve the problems that the roof drilling can not achieve the whole process of casing hole protection and gas drainage channels are blocked, the gas drainage technology of full-hole depth and large diameter socket pipe is studied. Making full use of the structural characteristics of ZDY-3200S type hydraulic drilling rig, by using full-hole depth casing protection technology, the socket pipe can be consistent with the track of drilling hole, and can reach more than 90% of the hole depth, so as to realize the socket pipe in place. The large diameter socket pipe greatly increases the gas circulation, effectively solves the plugging phenomenon in the drilling hole, improves the gas permeability of the casing, increases the gas extraction flow, prolongs the effective drainage time of the drill hole, and ensures the continuity of gas drainage. The results show that the technology can realize continuous gas drainage with full-hole depth, the concentration of gas extraction is basically unchanged, and the mixed flow rate of single hole extraction increases from 1.4 m³/min to 5 m³/min, increasing by 3.5 times, and effectively improving the drainage effect of roof drilling.