The entrance of a highway tunnel is located beneath a waterfall in a mountain gully, facing erosion threats during the rainy season that affect traffic safety. To address this, the study proposes a targeted anti-erosion design scheme taking into account structural safety, operational safety, landscape preservation, and cost control. The scheme effectively protects the tunnel entrance by moderately extending the open-cut section, installing a water-receiving pool on the top, and integrating a water interception and drainage system. The paper elaborates in detail on the design concept, process, key issues, and control points. Practice shows that this design not only effectively resists erosion, ensuring the structural stability of the entrance and driving safety, but also preserves the natural landscape of the gully waterfall to the greatest extent, achieving harmony between the tunnel and its surrounding environment. The research results provide valuable references for similar projects and offer new ideas for integrating safety, environmental protection, and aesthetics in tunnel entrance design.