Abstract: On the basis of the evolution laws of "three fields" and technological idea before gas drainage, during or after coal seam mining, the gas drainage technology with multi-application drilling for underground boreholes in coal mine is proposed. The key technology is that the underground boreholes play the role of geological drilling, hydraulic fracturing drilling, pressure relief drilling, goaf gas extraction drilling, and intercepting gas of surrounding rock and the adjacent layer. The good drainage effect is achieved by multi-application drilling engineering experiment.