As a kind of light and high strength material, SiC/Al composite has been widely concerned because of its excellent physical and chemical properties. In this study, molecular dynamics methods were used to construct SiC/Al composite material models with different SiC particle sizes. The results of tensile deformation simulation show that smaller SiC particle size is beneficial to higher tensile strength. As the tensile deformation gradually increases, the SiC particles are separated from the Al matrix on both sides along the tensile direction to generate voids, and then dislocations are generated from the void defects to nucleate and expand into the matrix to form plastic deformation. After adjusting the occupancy of C and Si on the SiC/Al interface, it is found that the bonding is stronger when the interface is rich in Si, and the generation of voids is more difficult, which strengthens the SiC/Al composite material.