In this paper, alumina ceramic coating of aluminum alloy surface was performed using micro-plasma oxidation (MPO) technology. Coating formed after short treatment time was found to consist of -Al2O3 and -Al2O3. Single -Al2O3 coatings can be gained by oxidation for 2.5 h. The growth velocity of coating thickness was 0.7 m/min during first 135 min, then that was constant. The surface density of coating was only 0.088 mg/cm2 at 15th min, then that increases gradually. The surface density increase presented a linear relationship during 15 min~60 min, and after 60 min the increase of surface density of coating is slow.