In the fault development section, due to the large change of coal and rock occurrence in the two walls of the fault and other factors, the fault drop became larger in the deep layer. The safe distance between the coal seam floor and the threatened aquifer was greatly reduced, which posed a serious threat to the coal seam mining. In order to solve the technical problem, the surface directional drilling technology was used to construct branch holes to detect the fault development near the top surface of the threatened aquifer, and the underground construction drilling was used to verify the fault development. According to the detection, the surface construction secondary branch holes were used to strengthen the threatened aquifer and fault zone, and the underground geophysical exploration and drilling methods were used to detect and verify the treatment effect, so as to transform the floor of the working face from broken block to complete block. The practice showed that this technology had obvious treatment effect on the fault and the threatened aquifer nearby, and provided a guarantee for the safe mining of the working face.