<p>This study investigates how geometric structure influences the mechanical behavior of skin-suture interfaces by analyzing the mechanical response and application of fractal interlocking structures at wound sites. First, a fractal skin interface was designed based on the Koch interlocking model, and tensile failure tests were performed on various suture structures using digital image correlation. The research focused on the progressive failure behavior of the second-order-tooth skin-suture interface, examining the effects of tooth tip angle, fractal order, and centerline distribution form on tensile performance. The preferred fractal parameters were then applied to a surface wrist wound example, and numerical analysis explored the interface’s mechanical response characteristics under a joint-bending load, confirming the fractal structure’s practical superiority. The results show that a smaller tooth-tip angle, higher fractal order, and sinusoidal centerline structure all improve the tensile performance of the skin interface. The design of the fractal interlocking structure significantly increases the critical value for interface damage jitter, providing valuable guidance for improving postoperative skin-wound healing in clinical suture practice.</p>