Abstract: Porous-type anodization is carried out on thin aluminum film deposited on silicon substrate by election beam evaporation technique. TIM examination of the obtained alumina film shows a much more less ordered pore arrangement compared with those produce from bulk aluminum under long anodization period condition. This discrepancy in pore ordering degree can be caused by many factors such as anodization period, applied electrolyte and voltage. Furthermore, a newly introduced crystallinity should also be carefully taken into account. Due to the polycrystalline structure of the thin Al film rather different from that nearly single crystalline of bulk Al, the interfacial region of its Al grains, which induce some extent of fluctuation in atomic density and relative anodizing rate along the direction of the pore development in comparison with grains themselves, will give an effect to the self-organized process during anodization by disturbing the electric field distribution at the pore bottom.