Plasma electrolytic oxidation (PEO), also named as micro-arc oxidation (MAO), is popular in enhancing corrosion resistance of valve metals. Unfortunately, the inherent defects ascribed to the fierce reaction during preparation damage the long-term stability of the coating. Recently, researchers have drawn some methods to address this issue by fabricating multilayered coatings and introducing sealing agents based on PEO-coated alloys. However, single passive physical barrier effect seems insufficient to satisfy the prolonged corrosion resistance and stability of the coating systems. Consequently, organic and inorganic corrosion inhibitors are introduced to endow the coatings with an active protective (self-healing) effect. The corrosion inhibitors usually function by forming a precipitation film or chelating on bare substrate. Besides the corrosion inhibitors, layered double hydroxides (LDHs), intrinsic self-healable organic coatings, metal organic frameworks (MOFs), etc., are also applied on the basis of PEO coating to construct multilayer active corrosion protection coatings. This chapter provides an overview of recent research and summarizes characterization methods for active protection, attempting to find new research ideas of active protective coatings on the basis of PEO coatings.