_{:TiO2 thin films were prepared by Atomic layer deposition on K9 glass. The crystal structure, optical properties and photocatalytic properties of the films at different deposition temperatures were characterized by XRD, SEM, AFM, spectrophotometer and ultraviolet-visible spectrometer. TiO2 thin films were amorphous at 25℃ and 120 ℃, anatase structure was obtained at 210 ℃ and 300 ℃. As the deposition temperature increases, the size of the film shrinks, the surface size decreases, the film becomes denser, and the lower the transmittance, the better the photocatalytic performance. The degradation rate of methyl orange solution can reach 47.16% under 12h visible light irradiation of TiO2 film (2mm * 2mm) prepared at 300 ℃. Increasing the sample surface ares in a tiling manner can significantly increase the degradation of methyl orange solution rate.}