Abstract: High level directional long drilling in coal seam roof is an important technical means of pressure relief gas drainage in coal face. Aiming at the technical problem of directional drilling of high-level hole in complex coal seam roof, a composite strong slag discharge directional drilling technology is proposed, a strong slag removal directional BHA with mud pulse while drilling measurement system and triangular spiral drill pipe as the core is designed, the principle of strong slag removal technology of triangular spiral drill pipe is analyzed, a complete set of composite strong slag discharge directional drilling equipment has been formed. The application research was carried out in 3314 coal face of Wangpo coal mine of Shanxi Tiandi Wangpo Coal Industry Co., Ltd. The results show that in the complex roof strata represented by mudstone, 6 high-level directional boreholes have been completed, the hole forming rate is 100%, the maximum drilling depth is 500m, the daily average footage is more than 70m, and the cumulative drilling footage is 2325m. The drilling efficiency and hole forming rate are greatly improved compared with the conventional directional drilling process. It provides a technical guarantee for the use of high-level directional long drilling in the roof instead of high drainage roadway to control the gas drainage in the working face and goaf, and support the safe and efficient production of the coal face.