Abstract: As known,porous alumina membrane is a type of template for fabricating nano-structural materials.By using electrochemical anodization method with two-step anodic oxidation and H₃PO₄ solution etching treatment,anodic aluminum oxide(AAO) membrane with nano-sized pore structure on the surface of high purity aluminum sheet was synthesized.SEM observation indicates that the membrane with ordered and hexagonally packed pore structure has been formed through the electrochemical anodization and the pore diameter is about 70nm.Compared with the one-step anodic oxidation,the AAO membrane obtained from the two-step anodic oxidation shows large improvement in the regularity of porous distribution and the arrangement of holes.It is also found that the subsequent etching treatment in a H₃PO₄ solution can remove the barrier layer on AAO membrane and improve the regularity of holes.Electrochemical anodization proves to be a simple approach to prepare high-quantity AAO membrane with ordered and hexagonally packed pore structure,which could provide an ideal model for synthesizing 1D nano-materials.