Abstract: Hydraulic fracturing was the key technology to weaken the hard roof of coal seam and solve the dynamic disasters such as strong underground pressure and large area hanging roof. Accurately understanding the propagation law of hard roof fractures during hydraulic fracturing is of great significance for precise fracturing construction and effect evaluation. Taking the hydraulic fracturing project of a mine in northern Shaanxi as the object, the microseismic monitoring technology was used to monitor the process of fracture expansion in the process of roof fracturing, reveal the law of roof fracture propagation law, evaluate the effect of roof hydraulic fracturing and discuss its influencing factors. The microseismic monitoring results indicate that in the process of hydraulic fracturing of the hard roof of the 4203 working face, the roof cracks dynamically expand on both sides with the progress of fracturing, and the final extension range of cracks on the side of transportation roadway is 26 ~ 33 m, and that of the auxiliary transportation roadway is 30 ~ 42 m. The verification of the pressure relief drilling show that the fracture range on the side of the auxiliary roadway is up to 42 m, which is basically consistent with the microseismic monitoring results, indicating that the fracture has been extended to the bottom of the pressure relief hole, and the hydraulic fracturing effect is better. In the process of hydraulic fracturing, the expansion range of fracturing fracture is positively correlated with pressure and fracturing time, and the expansion range of fracturing fracture is also related to the goaf. The results provide the groundwork for the extensive use of microseismic monitoring technologies in the coal mining industry and offer a scientific basis for precisely assessing the hydraulic fracturing effect of the hard top plate in the working face.