The ceramic oxide film on the surface of 7475 aluminum alloy was prepared by micro arc oxidation. The surface and interface morphology, chemical composition and phase were analyzed via SEM, EDS, XRD and etc. Energy spectrum analysis was conducted to analyze the distribution of chemical composition on the surface and interface. Adhesion strength of ceramic oxide film interface was measured by scratch. The results show that a layer of rough porous ceramic oxide film, whose chemical element is distributed correspondingly with its phase, is formed on the surface of 7475 aluminum alloy by micro arc oxidation. The Al2O3 mainly composed of α-Al2O3 and γ-Al2O3 is formed on the Al base by combining with diffusing O atoms, while the enrichment of Si atoms forms Si-Al-O phase. The ceramic oxide film is composed by gap layer, dense layer and film-substrate layer with thickness of about 50 μm.