Al2O3 ceramic coatings were directly prepared on 6063 aluminum alloy in borate electrolytes by micro-arc oxidation (MAO) technique. The phase composition, microstructure, elemental distribution, and micro-hardness of Al2O3 ceramic coatings were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and micro-hardness test. XRD results show that the coating consists of α-Al2O3 and γ-Al2O3. SEM results show that the pores with different sizes distributed all over the coating surface. Adhesion and tribological and wear tests were also performed. It was found that ceramic coatings with high hardness, excellent adhesion and wear resistance could be formed.