To improve the corrosion resistance of 45 steel,hot-dip aluminizing and anodic oxidation were adopted to prepare an anodic oxidation film with a certain thickness on the surface of the 45 steel.The effects of current density on the morphology,thickness and corrosion resistance of oxidation film were analyzed.The results reveal that the anodized coating of hot dip aluminized 45 steel is mainly composed of alumina layer,aluminized layer and aluminum-ferroalloy layer.Current density can affect significantly the thickness and morphology of the alumina film,so that the corrosion resistance of the oxidation film is affected.The thickness of oxidation film is increased with increasing in current density.Meanwhile,the size and area of the pores in surface of the alumina film are also increased with increasing in current density,therefore,the corrosion resistance of the composites is increased firstly and then decreased.After anodic anodized with a current density of 2.0 A/dm² for 30 minutes,the self-corrosion current density of the hot-dip aluminized 45 steel in 3.5% NaCl solution is decreased by 2 orders of magnitude compared with that of ones before anodizing while the charge transfer resistance is increased by 20 times,indicating that the corrosion resistance is improved significantly.