Abstract: This paper takes the multi-branch horizontal grouting well reinforced with limestone on the corresponding floor L8 in the 15011 coal seam working face of Zhaogu No.1 Mine as the research object. Pilot hole in treated limestone layer is designed and drilled to obtain the buried depth, gamma value, ROD of geometrical parameter and structural information, and to accurately design and control landing point of limestone layer of the main hole of multi-branch horizontal grouting well; optimizing the conventional multi-branch horizontal grouting well drilling tool assembly, preferring to centralizer with under-size symmetrical and ball centralizer with ball on the screw and under-sized protrusions to form a dual stabilized drilling tool assembly to reduce the drift of deviation and azimuth during directional and compound drilling and reduce the frequency of adjustment for branch hole trajectory and length of directional segment. Based on the above technical measures, accurate control of the multi-branch horizontal grouting well trajectory in the L₈ limestone layer has been achieved for stable drilling.