Technologic problems of top coal recovery ratio, rock burst, coal spontaneous combustion and gas accumulation induced by hard top-coal or roof's fall in coal mining were introduced. Current research and development trend of hydraulic fracture weakening for hard top-coal or roof was analyzed, including the law of crack expanding induced by hydraulic fracture in rock mass, mescoscopic structure alteration of cracked rock mass by seepage pressure and its macroscopic mechanics response, controlling technology of hydraulic crack's expanding, the technology of enveloping drillbore and weakening effect monitoring.