Abstract: The branch hole is the key to ensure the long-distance drilling of directional hole along the target stratum, improve the coverage of directional drilling and accurately explore geological abnormal bodies. The principle, advantages and disadvantages of the main sidetracking branch technology in coal mine were analyzed. Taking the low speed grinding and hang sidetracking branch without hole bottom as the research object, the sidetracking branch mechanical model was established, and the calculation formula and influence law of the lateral force of the branch sidetracking was given; the dynamic process of hang sidetracking was analyzed, and the drilling points in the initial, middle and final stages of sidetracking were summarized; the numerical model of branch transition section stability analysis was established, the influence of coal and rock mass failure depth on the stability of branch transition section was studied, and the suggestions for safe drilling in branch transition section were given. The field application were carried out in Chengzhuang Mine with branch coal seam directional hole and Qidong Mine with comb floor directional hole, the maximum number of branches in a single hole is 77, the sidetracking success rate is 100% with the safety is 100%, which will provides a technical guarantee for the role of near horizontal directional hole in coal mine.