The WO3 film was prepared by dip coating method with WCl6 as the soure of tungsten and P123 as the structure-directing agent. The crystalline phase and microstructure of the film were characterized through XRD and TEM techniques, respectively. It was found the film annealed at 300°C for 4h mainly was amorphous WO3 with a little monoclinic WO3. The TEM micrographs revealed the film was partly ordered mesoporous and the mean pore diameter was about 5nm. The measurements of the cyclic voltammetry suggested that the WO3 film had a good electrochromic reversibility performance. The ratio of amount of charge intercalated and amount of charge deintercalated during the cyclic voltammetry, was over 99%. The film possessed a very short respond time which was only about 3.1s.