TiO_2 thin films were prepared with Ti_2O_3, Ti_3O_5 and TiO_2 as raw materials, by electron-beam evaporation deposition, using O 2- ion beam (O_2 purity up to 99.99%) as auxiliary means. The crystal structures of the samples were inspected by the X-ray diffraction (XRD) method, and the evaporation character of various raw materials was analyzed. Transmittance spectra were measured through a U-3310 spectrophotometer (wavelength ranging from 200 nm to 900 nm). The refractive index n and the thickness of films were determined from transmission spectra. The experimental results show that the thin films taking Ti_2O_3 as their raw material have a strong absorption, when taking Ti_3O_5 and TiO_2 as raw materials, the thin films would have good optical properties. The experiments also show that, the crystal structure of all thin films is amorphous before post-annealing and the Ti_3O_5 is a congruent evaporation phase in the Ti-O system. TiO_2 thin films were prepared with Ti_2O_3, Ti_3O_5 and TiO_2 as raw materials, by electron-beam evaporation deposition, using O_2 ion beam (O_2 purity up to 99.99%) as auxiliary means. The crystal structures of the samples were inspected by the Transmittance spectra were measured through a U-3310 spectrophotometer (wavelength ranging from 200 nm to 900 nm). The refractive index n and the thickness of films were determined from transmission spectra. The experimental results show that the thin films taking Ti_2O_3 as their raw material have a strong absorption, when taking Ti_3O_5 and TiO_2 as raw materials, the thin films would have good optical properties. The experiments also show that, the crystal structure of all thin films is amorphous before post-annealing and the Ti_3O_5 is a congruent evaporation phase in the Ti-O system.