Vanadium oxide films with different thicknesses were deposited on quartz substrates at room temperature by a thermal evaporation system. The structure and morphology of the vanadium oxide films were investigated by X-ray diffraction, Raman spectra and atomic force microscopy(AFM), respectively. Transmittances of the films were measured by spectrophotometer. Refractive indices, extinction coefficients and band gap of the films were calculated from all transmittance data. The experimental results show that the structure of the samples is amorphous phase. The main chemical composition of the films is V2O5 and it contains a little of VO2. All pellets on the film surface stick together, the surface roughness and surface grain size decrease with the thickness increasing. In addition, when the thickness of the film increases from 200 to 450 nm, the refractive index increases but extinction coefficient decreases, and the band gap energy decreases from 2.67 eV to 2.45 eV.