Abstract: As the depth of coal mining increases,the control of the overlying rock stratum becomes crucial. To investigate the effects of different confining pressures and borehole angles on hydraulic fracturing cracks,this paper conducted a simulation experiment of hydraulic fracturing crack propagation using similar materials. The experimental results show that hydraulic fracturing cracks mainly propagate along the direction perpendicular to the minimum principal stress,and the deflection angle of the crack is significantly affected by the borehole angle and the difference in principal stress. The larger the borehole angle or the larger the difference in principal stress,the easier and more obvious the deflection,and the faster the crack propagation speed in the case of a larger borehole angle or a smaller difference in principal stress. The experiment reveals the characteristics of hydraulic fracturing crack extension under different conditions,providing theoretical support for the optimization of parameters in the application of hydraulic fracturing for pressure relief in hard roofs.