Abstract: In the process of permeability-enhancing blasting in deep inclined coal seams, energy transmission is highly complex and fracture propagation paths are easily affected by coal-rock interfaces. However, the influence of interface inclination on blasting-induced damage and fracture evolution in coal–rock masses under high in-situ stress has not been fully clarified. Taking the No.9 coal seam in the Huaibei mining area as the engineering background, composite coal–rock specimens with four typical interface inclinations (0°, 15°, 30° and 45°) were prepared. A self-developed biaxial stress loading blasting simulation system was used to apply equal biaxial confining pressures, and blasting similarity model tests were carried out. Combined with surface crack mapping, ultrasonic CT imaging and stress time-history monitoring, the distribution of post-blast damage zones, the characteristics of stress-wave propagation, and the evolution of fracture networks were analyzed. An LS-DYNA numerical model consistent with the physical tests was further established to investigate the effects of interface inclination on fracture evolution and damage distribution. The results show that: Interface inclination significantly affects the distribution pattern of blasting-induced surface fractures. At small interface angles (0° and 15°), cracks exhibit a nearly circular plan distribution with good continuity across the interface, and fractures in the far-field coal area propagate radially. At large interface angles (30° and 45°), fracture deflection is enhanced; elongated fractures develop along the interface, cross-interface fractures become discontinuous, and the damaged extent in the coal seam is reduced. For small interface angles, the damage zone expands approximately circularly and crosses the interface into the coal seam, where the wave-velocity reduction of the coal mass reaches 22%–36%. For large interface angles, damage is confined near the interface, the coal wave-velocity reduction is only 8%–16%, and the transmitted energy attenuates markedly. Under small interface angles, the peak stress at coal-side measuring points reaches 72.3% of that at the rock side, with a high transmitted amplitude ratio and pronounced oscillatory fluctuations. At large angles, the amplitude ratio drops to 56.9%, the coal-side stress attenuates by 27.5%, and energy dissipation is dominated by wave reflection and shear slip. Numerical simulations confirm that small interface angles are conducive to the formation of radially distributed fracture networks driven by normal stress transmission. At 0°, fracture orientations are uniformly distributed, the rose diagram is nearly annular, and anisotropy is weak; at 30° and 45°, the dominant fracture orientations become markedly convergent and rotate with the interface angle, further verifying the constraining effect of interface geometry on fracture development. These findings provide important theoretical guidance and engineering references for the optimization of permeability-enhancing blasting parameters in inclined coal seams, the improvement of efficient gas drainage technologies, and the prevention and control of deep dynamic disasters in deep mining.