La3+ doped TiO2 films were prepared through innovative ultrasonic-sol-gel method. The cavitation effect of ultrasound could contribute to grain refinement and uniform dispersion. The composition, structure and performance of the obtained material were characterized by XRD, SEM, FT-IR and UV-vis. Our results indicate that La3+ doping could prohibit the phase transformation of TiO2 (i.e., from anatase to rutile) and increase phase-transition temperature and restrain grain growth. The crystalling phase composition of La3+ doped TiO2 films is anatase, and the particle size is from 6 to 17 nm. In addition, La3+ doping can bring the red shift of the optical absorption edge of TiO2, and the degree of red shift increases with the increase of La3+ doping amounts and decreases with the increase of temperature. Thin film thickness is found to be 70-80nm with a smooth surface.