Abstract: The interfacial thermal mismatch stress will generate at the reinforcement/metal matrix heterogeneous interfaces during the cooling process of the metal matrix composites (MMCs), due to the large mismatch of the coefficient of thermal expansion (CTE) between the reinforcement and the metal matrix. The interfacial thermal mismatch stress can be released in the form of the various kinds of defects near the interface, while the thermal mismatch stress will be retained in the form of the thermal residual stress away from the interface. The type, size, and density of defects and the thermal residual stress show the significant influence on the mechanical properties of MMCs. To provide the theoretical and scientific foundation for the further design and optimization of the MMCs interface structure, the effect of interfacial thermal mismatch on the mechanical properties of MMCs was investigated in this paper, and the generation of thermal mismatch defect and thermal residual stress was described.