In order to investigate the effects of doping boron on the self-cleaning properties of TiO2 thin films, sol-gel method was employed to prepare TiO2 films with various amount of boron on the glass substrates. Atomic Force Microscope (AFM) and X-ray diffraction (XRD) were carried out to investigate the effects of boron on the microstructure and crystallization behavior of the thin films. The photocatalytic activity and the hydrophilicity of the films were also measured. The results showed that the photocatalytic activity of TiO2 films was improved by doping boron, and its hydrophilicity wasn’t destroyed. This can be ascribed to the enhancement of the surface energy, which was caused by the reduction of the crystal grain size of TiO2.