Reservoir stimulation is crucial to the successful exploitation of hot dry rock geothermal resources. In this paper, a new fracturing method using liquid nitrogen as fracturing fluid to stimulate hot dry rock reservoirs is proposed. Compared with conventional water-based fracturing fluid, liquid nitrogen combines the dual effects of fluid pressure and ultra-low (− 196 °C) temperature, so its crack initiation and propagation characteristics are significantly different from traditional hydraulic fracturing. Based on the self-developed high-temperature granite liquid nitrogen fracturing experimental equipment, we carried out liquid nitrogen fracturing experiments for granite at different temperatures. Taking the fracture initiation pressure, fracture surface strike and fracture complexity as evaluation indicators, the fracture initiation and propagation law of liquid nitrogen fracturing is obtained by comparing with the conventional hydraulic fracturing. The experimental results illustrate the influence of initial temperature of granite, liquid nitrogen cycle time before fracturing, in-situ stress difference coefficient, and length of open hole section at bottom on the effect of liquid nitrogen fracturing. The three-dimensional morphology of the main fracture of granite was reconstructed by the three-dimensional morphology apparatus, and the tortuosity and roughness of the liquid nitrogen fracturing cracks were analyzed and calculated. This research reveals the fracture initiation and propagation mechanism of liquid nitrogen fracturing granite, which is expected to provide an important experimental basis for evaluating the feasibility of liquid nitrogen fracturing in hot dry rock reservoirs.