The UV-Vis absorption spectra of TiO2 and La-doped TiO2 thin films are shown in Fig. 4. It indicates that the absorption edge shifts toward longer wavelength for La- doped TiO2 thin films and the light absorption ability was greatly improved. When the content of La was 0.3 wt.%, the absorption ability of TiO2 thin films toward the light of ultraviolet improved to the greatest (about 3.7). It clearly indicated that the content of La had significant effect on the photocatalytic activity. Fig. 5 is the effect of La-doping on the photocatalytic activity. With the in- creasing of the content of La-doping from 0 to 0.3 wt.%, the degradation efficiency increased from 80% to 92% (Fig. 5). However, a decrease in photocatalytic activity was exhibited when the concentration of La became too large. The basic law of data change was in good agreement with the reported literatures