Abstract: In order to solve the problem of broken roof in mining under the direct cover of caving zone,the idea of ground grouting reinforcement was put forward, and the drilling technology was studied systematically. According to the actual stratigraphic distribution and the characteristics of drilling through the collapse zone, in order to ensure the slurry to reach the target layer smoothly, the second opening structure drilling hole was designed. The high-quality low solid bentonite flushing fluid was selected to solve the hole wall collapse and other accidents. At the same time, the technical system of accident prevention measures was established. On this basis, taking the 7228 working face of Xutuan coal mine in Huaibei mining industry as an example, the drilling effect was analyzed. The research shows that the designed second opening structure drilling hole effectively guarantees the smooth construction of the drilling, and the exposed bedrock position is basically consistent with the original data. Basically, the strata affected area of 71 coal goaf and characteristics of fracture development have been basically identified. And at the same time, it also proves that the crack reinforcement effect of goaf is good through simple hydrological observation. The research results provide technical support for the drilling project of ground grouting to transform broken roof.