Abstract: This paper adopts the constant voltage method and uses 18 wt% sulfuric acid solution to prepare the anodic oxidation film layer of SiC particle reinforced aluminum matrix composites. The influence of SiC particle size on the anodic oxidation voltage, current density stability and the thickness of the anodic oxidation film layer of the aluminum matrix composites is studied. Through the salt spray test, the protective effect of the anodic oxide film layer on the aluminum-based composite material was verified. Through the tensile test, the influence of the anodic oxide film layer on the mechanical properties and hardness of the aluminum-based composite material was examined. The results show that the finer the particles are, the higher the oxidation voltage of the anodic oxide layer will be, the better the current density stability will be, and the thicker the anodic oxide layer will be, the more uniform and dense the layer will be. The thickness of the anodic oxide layer is over 8 μm, and it can achieve a protection level of 10 for the aluminum-based composite material. The anodic oxide layer has almost no effect on the tensile properties of the material, but significantly improves the surface hardness of the material.