Abstract: In order to analyze the effect of horizontal stress difference coefficient on hydraulic fracturing fracture formation, PFC^2D software was used to simulate hydraulic fracturing. The parallel bond model was used to simulate uniaxial compression and Brazil splitting test for parameter calibration. The number of fracturing fractures generated under different conditions after a certain time step was calculated by using calibration parameters for simulation. The fractal dimension was calculated by binarization of hydraulic fracture images. The analysis results show that when the horizontal stress difference coefficient is large, the fracture direction is controlled by the maximum horizontal principal stress, and it is easier to form a single through crack, while when the horizontal stress difference coefficient is low, the control effect of the maximum principal stress is weakened, the range of micro-cracks will be expanded, and the hydraulic fracture complexity is relatively higher.