Abstract: Transparent TiO₂ thin films were prepared by liquid phase deposition method. The UV-Vis absorbing property and change of hydrophilicity under UV illumination of as-prepared films were investigated. The results show that, they exhibited similar UV-Vis absorbing property and their hydrophilicity was all increased by UV illumination whether the films were annealed or not. The films annealed can be entirely wetted by water after UV illumination for certain time. X ray photoelectron spectrum analysis of surface of the films shows that the difference of hydrophilicity of the films before and after annealing was due to of increase of Ti-O bonds and TiO₂ composition, which makes more Ti⁴⁺ change into Ti³⁺ under UV illumination thus facilitates adsorption of water.