Abstract: In view of the thick coal seam overlying the roof of the open-off cut in the fully mechanized caving face, the con-ventional measures cannot effectively weaken the basic roof during the initial caving. A long-short hole mul-ti-dimensional hydraulic fracturing method is proposed. This method can complement each other 's advantages in construction time and space under the premise of construction safety, and weaken the main roof. Based on the en-gineering background of 12-2 upper 111 fully mechanized caving face in Jinjitan Coal Mine, the movement law of overlying strata under long-short hole multi-dimensional hydraulic fracturing is analyzed by theoretical calcula-tion, numerical simulation and field test. The results show that the initial fracture distance of hard roof after long-short hole multi-dimensional fracturing is 10 m lower than that of short hole fracturing model, and the roof collapses step by step, and the pressure is more moderate. After the initial caving test, the effect of fracture propa-gation was evaluated by field construction records such as water pressure monitoring, borehole peeping, and water running observation. It shows that short-hole fracturing forms a dense and complex cross-fracture network at a low position, and long-hole fracturing forms a regional fracture at a high position, so that the large rock mass acts on the short-hole fracturing area to achieve timely roof caving. The roof caving and weighting during the initial min-ing period of 111 working face were tracked, and compared with the adjacent 113 working face. The initial weighting interval was reduced to 40.8 m, which indicated that after long-short hole multi-dimensional hydraulic fracturing, the roof could fall in time and enrich the goaf, and good safety effect was achieved.