Porous anodic aluminum oxide films with nanometer porosity have been fabricated by electrochemical method in the aqueous solution of oxalic acid. Regular porosity in about 38 nanometer size was observed using atomic force microscopy. Excitation and Emission spectrum were obtained by using F-4500 fluorometer.Compared with aluminum of not oxidize , the former has a broad peak band at about 280 nm~340 nm and a second peak at 253.8 nm in excitation spectrum, including a broad peak band at 417.4 nm in emission spectrum, while the latter without any obvious peak in either excitation or emission spectrum. Blue emission was obtained when sample was excited using 248 nm and 355 nm laser. The photoluminescence was attributed to the local structure caused by unbalance of Al and O as well as involvement of electrolyte during oxidization process, at the same time, quantum localization effect affected its optical properties.