A pure TiO2 colloidal solution for a catalyst with a high photocatalytic activity was obtained by thermal hydrolysis of titanium tetra-iso-propoxide (TTIP). The TiO2 film on pyrex plate, which was dip-coated with the colloidal solution, was characterized by XRD and SEM analyses. It was confirmed that the TiO2 film exhibited a uniform anatase structure with a particle size <45 nm and the film thickness was about 200 nm in one-time coating. To investigate the performance for 1,1'-dimethyl-4,4'-bipyidium dichloride (Paraquat) destruction, the TiO2 film was directly fixed on the UV-Iamp by the dip-coating method. The conversion of Paraquat remarkably increased by the film prepared by the hydrothermal method compared with the film prepared by the sol-gel method; in particular, the conversion reached above 95% after 15 h. In addition, the TiO2 film prepared by the hydrothermal method was stably attached on the UV-Iamp surface after reaction. But the film prepared by the sol-gel method was partially taken off the UV-lamp surface. Therefore, in this study, it was confirmed that the hydrothermal method was very reliable method for the synthesis of TiO2 thin film with high catalytic performance.