<p>Hydraulic fracturing is widely employed in the exploitation of underground resources, and the variation in natural fracture width plays an important role in the effectiveness of hydraulic fracturing. In this work, a Hydro-Mechanical Coupling Model (HM) was primarily established to explore the influence of fracture width, fluid viscosities, and fracture angle on natural fracture transformation based on the Peridynamics (PD) method. Then, the accuracy of the PD model was validated by comparing the numerical simulation results with analytical solutions. Ultimately, a series of numerical models were established to numerically investigate the influence of fracture widths, fluid viscosity, and fracture angles on the development of natural fracture. Results show that a larger initial natural fracture width or a decrease in fluid viscosity can increase the pore water pressure in the natural fracture, which in turn leads to a better natural fracture modification. The initial width of the natural fracture and the fluid viscosity directly influence the rate of variation in natural fracture width. The angle of natural fracture has a relatively small impact on the pore water pressure in fractures, while a greater impact on the displacement field surrounding the fracture.</p>