<p>Studying how natural fracture networks (NFNs) interact with hydraulic fractures is of great significance for the exploitation of unconventional reservoirs with well-developed NFNs. The arrangement and combination of unit modules are used to simulate NFNs. The parameters of the natural fracture network are adjusted by varying the inclination angle between small rock block units, network density, and cementation strength. True triaxial fracturing laboratory experiments were performed to investigate the influence of NFNs on hydraulic fracture propagation under different conditions during horizontal well hydraulic fracturing, including natural fracture network (NFN) inclination angle, density, cementation strength, and horizontal stress difference. The study found that the smaller the angle between the natural fracture and the maximum horizontal principal stress, hydraulic fractures tend to propagate along the NFN. Conversely, they are more likely to cross the NFN. As the density of the NFN increases, the hydraulic fracture network gradually transforms into a complex fracture network dominated by natural fractures. Higher NFN density enhances fracture area and complexity. Lower cementation strength facilitates NFN activation, and the more likely branch fractures are to form. Conversely, a single planar fracture is more likely. Lower horizontal stress differences reduce in-situ stress control over fracture propagation, and the more likely the hydraulic fracture is to extend along natural fractures. Conversely, the more likely the hydraulic fracture is to directly cross natural fractures, resulting in lower fracture complexity. Fracture propagation direction analysis confirmed that the modified R&amp;P criterion better matches field conditions and can satisfy the applicability of intersection criteria under more complex circumstances. This study offers practical insights for fracturing well-developed NFN reservoirs.</p>