Transparent anatase TiO2 nanometer thin films were prepared via the sol- gel process using the TiO2 sol solution on soda- lime glass. XRD patterns of films show that the single anatase phase is precipitated when the thickness of TiO2 films is over 0.46 μ m and there is some orientation effect in (101) direction. However, XRD patterns show almost no peaks of anatase when the thickness is smaller than 0.46 μ m, which is attributed to an insufficient content of titanium dioxide. The transmittance of TiO2 films decreases, the average crystalline size of TiO2 films increase and the absorption edge wavelength of TiO2 films becomes larger with increasing cycle times and film thickness. The chemical compositions of the films were analyzed with X- ray photoelectron spectroscopy (XPS). Experiment results show that besides Ti and O elements, there is a certain amount of residual carbon from the starting organometallic components and a small amount of sodium and calcium ions diffused from the glass substrates.