Abstract: Based on the principle and existing technology of gas drainage by high level directional borehole, and with regard to high-level directional borehole which was difficult to be realized in the complex roof strata of Huainan Mining Area, the pore forming technical measure combined with reinforcement strata by high pressure grouting, dredge drilling by reaming technology and rapid crossing broken layer by large angle was put forward. Three roof high-level directional boreholes with 510 m depth and 153 mm bore diameter were successfully actualized for the first time in the Huainan Mining Area. High-level large diameter directional borehole technique which was suitable for complex roof strata in Huainan Mine Area was formed. This technology provided a new technical approach for gas drainage in similar condition mining area. Specific to the problems of frequent reaming, low drilling efficiency in hard rock, low fishing accuracy of conventional fishing tools in large diameter drilling and difficulty of entering bushing, the solutions were proposed, and which provided ideas and directions for subsequent research.