In order to improve the corrosion resistance of the sintered NdFeB permanent magnets, Al2O3 ceramic coatings were prepared by a two-step micro-arc oxidation process in an aluminate solution. During the micro-arc oxidation process, the voltage-time curve could be divided into four regions consistent with the valve metals. The coating exhibited a typical micro-arc oxidation porous surface with the thickness of ~5 μm, and was only composed of Al2O3 crystalline phase with some Fe elements and a few Nd and P elements. The surface roughness of coated NdFeB magnets was higher than that of uncoated sample, while the corrosion resistance was enhanced by one order of magnitude. Unfortunately, the magnetic properties (remanence and maximum energy product) of coated NdFeB sample decreased in different degrees.