Aiming at the problem of hard roof overhanging in the triangle area of 8230 fully mechanized caving face in Tashan Coal Mine, by analyzing the formation mechanism of overhanging, the carbon dioxide pre-splitting blasting technology is proposed to control the roof. A differential borehole layout scheme including coal caving hole ( KA1 ) and roof cutting hole ( KB1-KB3 ) was designed, and F-57 type fracturing device was used to realize long borehole segmented fracturing. The engineering application shows that after fracturing, the caving step distance of the end triangle area is reduced from 40 m to 18 m, and the initial weighting step distance is shortened from 78 m to 35 m, with a decrease of 55%. The convergence deformation of the roof and floor of the roadway is reduced by 48.3%, which effectively avoids the hurricane disaster caused by the sudden collapse of the suspended roof. The research results provide a technical reference for the safe mining of fully mechanized caving face under the condition of hard roof.