Microarc oxidation (MAO) is a kind of technology that causes partial plasma discharge by applying high voltage to melt metal oxides and form ceramic coatings on light metal (aluminum, magnesium and titanium) and their alloys with the thickness of tens of microns to hundreds of microns, which have the advantages of wear resistance, corrosion resistance, electrical insulation, etc. Due to the inherent plasma discharge phenomenon in the MAO discharge process, the discharge gas and molten metal oxide will be ejected from the inside of the coating. During the ejecting process, defects such as discharge channels and micro-cracks are formed under the rapid quenching effect in the aqueous solution. This defect structure has a high specific surface area and can serve as a penetration channel for the corrosive medium, affecting the overall corrosion resistance of the MAO coating. Therefore, avoiding or sealing these discharge channels is crucial for improving the corrosion resistance of coatings and enhancing the large-scale application of light alloys.