Aiming at the problem that it is difficult to quantify the effect of fractured rock strata due to insufficient research on the evolution law of fracturing anti-scour fracture under the condition of hard roof engineering scale, the 3106 working face of Menkeqing Coal Mine is selected as the engineering background, and the research on long-hole hydraulic fracturing of narrow coal pillar high thick hard sandstone roof is taken as the starting point. Borehole leakage rate and transient electromagnetic technology were selected to study the temporal and spatial evolution law of rock fracture development, borehole leakage rate and transient electromagnetic resistivity at different strata before and after hard roof fracturing, and quantify the development law and expansion range of overburden rock fracture before and after the hard roof weakening of narrow coal pillar, providing theoretical guidance for the study of hydraulic fracture evolution law and influence range. The results show that: When the borehole is in the region affected by mining movement, the borehole leakage before and after fracturing does not change significantly. When the borehole is in the region where the original rock fracture is not developed, the borehole leakage before and after fracturing presents a multiple increase. The change of borehole leakage before and after fracturing obviously indicates the fracture expansion in the upper and lower ranges of the fractured formation. The range of fracture propagation in fractured formations is quantified from the engineering scale, and the resistance reduction phenomenon occurs when the water content in fractures increases due to the interpenetration of the fracture network in this formation is verified by the transient electromagnetic technology, which indicates that the development effect of hydraulic fracture is good, and the reliability of the weakening effect of hard roof is verified, providing theoretical guidance for the study of the evolution law and influence range of hydraulic fracture.