Hydraulic fracturing technology is one of the most important technical means to successfully realize the exploitation and utilization of HDR resources. Numerical simulations can accurately predict hydraulic fracture propagation. Cohesive- zone- model was used to simulate the hydrofracture propagation characteristics of dense granite, and granite with natural fractures. The hydraulic fracture of dense granite is a simple crack. The existence of natural fractures increases the complexity of hydro- fractures. The hydrofracture development of tight granite can be divided into two phases: compression and expansion. Hydraulic fracturing can be complicated when natural fractures exist, and the length and width of hydraulic fractures are respectively 5. 7 and 1. 7 times those in dense granite. The formation of a complex fracture network needs special fracturing technology. These research results can provide theoretical support for hydraulic stimulation of an EGS reservoir.