<p>Improving the tribological performance of gear surfaces is of great significance for extending service life and reducing energy consumption. In this study, inspired by the semi-ring structure of loach scales, semicircular surface textures were designed and further optimized using a topology optimization approach. Five types of textures with different geometries and arrangements were fabricated by laser marking, including semi-ring textures (BS), topologically optimized unidirectional parallel textures (TUP), topologically optimized unidirectional staggered textures (TUS), topologically optimized opposed parallel textures (TOP), and topologically optimized opposed staggered textures (TOC). SnAgCu solid lubricant was subsequently filled into these textures to prepare five self-lubricating samples, and their tribological performance was systematically investigated under both dry friction and oil-lubricated conditions. The results show that under dry friction conditions, the TUS sample exhibits reductions of 4.56% in the coefficient of friction (COF) and 64.77% in the wear rate compared to the smooth sample (SS). Under oil-lubricated conditions, the TUS sample demonstrates decreases of 19.2% in COF and 78.78% in wear rate relative to the SS sample. Overall, the topologically optimized textured surfaces exhibit superior tribological performance under different operating conditions, and appropriate texture arrangements are found to be more effective in mitigating wear of the AISI 4140 steel substrate.</p>