When drilling holes in soft coal seams of high gas mines, it was prone to cause accidents such as nozzle holes, pinch drills, top drills, and poor drainage and slag discharge. In order to control the consequences caused by the nozzle hole, the Gucheng Mine was taken as an example to upgrade and improve the drainage hole-proofing device, which focused on solving the problem that the original anti-injection device was not tightly sealed and the slag discharging pipe was easy to block. The φ108 tube with insufficient negative pressure, the slag cinder was not easy to be discharged, and the observation was inconvenient. After the downhole test, the improved new anti-injection device could significantly reduce the drilling construction time and the return air flow in the drilling field, increase the drilling hole formation rate and improve the safe mining of the working face.