Some kinds of particular functions possessed by natural organisms are often formed by coupling up the multiple typical features on their body surfaces. Inspired by the coupling phenomenon in biological system, the medium carbon steel specimens with the coupling effect of non-smooth mechanical property and microstructural features were fabricated by laser processing. Thermal fatigue behavior of specimens with biomimetic coupling surface was investigated and compared. The results confirmed that such a biomimetic method has the beneficial effect on improving the thermal fatigue property of medium carbon steel specimens. The related mechanisms behind the biomimetic coupling effect for explaining the enhanced thermal fatigue resistance were discussed preliminarily.biomimetic coupling, medium carbon steel, thermal fatigue, non-smooth mechanical property, microstructural feature, laser processingIn biological system, some kinds of functional characteristics on the body surface of plants and animals are often resulted from the synergic action that combines multiple different factors associated with their surface functions. These factors include geometry, structure, chemical composition, bioelectricity, flexibility, liquid secretions, etc, of the body surface [1] . The effect that the performance of the organisms or their parts is strongly enhanced by synergy of different factors in a well combinated manner can be called the coupling effect. The biological coupling endows the body surface of living creatures with many excellent, even special functions. For example, the coupling effect of the configuration of pangolin claws and the non-smooth morphology of their claw scales, makes them have the exceptional ability to reduce the adhesion and frictional resistance of soil [2] ; through coupling of the protuberance-shape morphology with different structures as well as hydrophobic materials on the surfaces, lotus leaves have the amazing waterrepellent and self-cleaning functions [3] ; the outstanding abrasive-erosion-resistant characteristic possessed by the desert lizards, can be ascribed to the coupling effect of the scale-shape non-smooth morphology and the multilayer flexibility of their body surfaces [4] , as shown in Figure 1(a)-(c). Moreover, the remarkable fractureresistant function owned by organisms is reflected typically in the leaf vein structure of trees, as shown in Figure (d). This structure with the coupling effect of different microstructures and non-identical mechanical properties, between the rigid veins and the flexible mesophyll, makes the leaf more resistant to tearing and breaking by wind.