The Er3+-doped Al2O3 optical films have been prepared on SiO2 substrate by the sol-gel method and the dip-coating process, using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with the addition of erbium nitrate [Er(NO3)3?5H2O]. The surface morphology and structure of the 0.01 (mole ratio, ibid below) Er3+-doped Al2O3 film have been analysed by the scanning electron microscope (SEM), atomic force microscope (AFM), differential thermal analysis-thermogravimetric analysis (DTA-TG), and X-ray diffractometer (XRD). The 0.01 Er3+-doped γ-Al2O3 film with a thickness of 8 μm through 15 dipping coating cycles, which possesses a face-centered cubic lattice with a (110) preferred orientation, is obtained from 0.01 Er3+-doped γ-AlOOH gel sintered at 900 ℃. The addition of 0.01 Er3+ in the γ-Al2O3 has no evident influence on the phase structure and preferred orientation of the film. The homogenous and porous 0.01 Er3+-doped γ-Al2O3 film has a crystal size of 30～100 nm, a pore size of 50～100 nm, and a surface roughness of 10～20 nm. The photoluminescence (PL) spectrum centered at 1.533 μm with the full width at half maximum of 36 nm is observed for the 0.01 Er3+-doped γ-Al2O3 film, which is attributed to the intra-4f transition between the first excited (4I13/2) and the ground state (4I15/2) of Er3+.