Aluminum foils were fabricated by two different methods——evaporation and extrusion moulding. Depth distribution of surface elements and chemical components were analyzed by Auger Electron Spectroscopy (AES). Also the thickness of the oxidation layer exposed in ambient with different times was measured. According to the experimental results, the oxidation layer with saturated oxidation is mainly composed of Al2O3 and its thickness is about 7.5 nm. The throretical transmittance of the foil is then modifed by the formula I=I0.exp［-μ(E).(ρd)］. For comparison, experimental measurements of the transmittance are done on the Beijing synchrotron radiation facility, which are consistent with the throretical value within a maximum difference of 11%.