Al films (about 40 nm) were prepared on quartz substrates by thermal evaporation technique, and subsequently annealed in air for 1h at temperature ranging from 600 to 1300 degrees C. The characteristics of the annealed films were investigated in this paper. The measurement results of XRD and Raman show that crystalline phase transformations of the annealed films will convert from gamma, gamma and alpha, up to alpha-Al2O3 with the increasing of the annealing temperature at 600 degrees C, 1200 degrees C, to 1300 degrees C. AFM and transmission spectra reveal the effects of phase transformations on their morphology and optical properties.