Abstract: Coal-based hydraulic fracturing AR weakening the principles and roof fracture instability theory, physical simulation experiment study of hydraulic fracturing of coal seam roof rupture affect instability. Test showed that: after seam hydraulic fracturing, stepped roof overhang directly exposed length is shorter than when no seam hydraulic fracturing, fracturing the immediate roof is more broken, no strong roof pressure; after fracturing, in advance periodically breaking the old roof instability, shorten the main roof breaking stride, weakening the hard roof to alleviate rock burst, overlying rock broken sink gradually expanding the scope and the vertical hydraulic fracture crack tip is elliptical parabolic boundary; after fracturing, support load overall decrease, resulting in greater pressure on the roof to crack when excessive pressure, joint action by its holder pressure increase briefly, hydraulic fracture extension extended to rock, rock formation to the seam between Loaded Save small. The similar simulation test has an important reference value for the coal mine hydraulic fracturing weakening of the top plate main surface coal mining and management, to provide protection for coal mine production safety.