Abstract: In this paper,anodic oxidation and microarc oxidation method were adopted to form insulating films on 5A06 aluminum alloy.The microstructure,phase,insulance,leak current and breakdown voltage of the films were investigated covering thermal shock ability of the films against liquid nitrogen.The results showed that the microarc oxidation film is composed of γ-Al₂O₃ while the anodic oxidized film is composed of noncrystalline phase.For the anodic oxidized film and the microarc oxidized film,the breakdown voltage at DC or AC mode are both higher under dry circumstance than that under moist circumstance.Under the same current mode,the thicker the film,the higher the breakdown voltage is.For a given film thickness,the anodic film's ability against voltage breakdown is higher than that of microarc oxidation on matter under dry or moist circumstance,while under dry circumstance the insulation resistance rate of microarc oxidized film is higher than that of anodic oxidized film.Several thermal shocks of the anodic oxidized film and microarc oxidized film against liquid nitrogen show that the interface bonding between oxidation film and 5A06 aluminum alloy is strong.Owing to the good insulating properties and thermal shock performance,the anodic oxidized film and microarc oxidized film can be applied to electric power equipments working in low temperature.