Abstract: TiO₂ thin film crystal structures have been studied as functions of d eposition temperature and annealing temperature.The films have been characterize d by X-ray diffraction and Raman spectra.Films deposited on Si substrates are a morphous at 110～250 ℃，anatase at 350～500 ℃and rutile above 600 ℃.After bei ng annealed at 600 ℃,the films are anatase,and annealed above 800 ℃，the struc ture of the films is rutile.The deposition rate is strikingly increased by addin g oxygen in the reactant gas,but the oxygen does not effect the structure of the films.