Abstract: In this paper, stable WO3 sol and TiO2 sol with well-dispersed granules and narrow dimension distribution were prepared by the sol-gel method. Thin films were obtained by dip-coating and spin-coating methods and they were then assembled into a photoelectrochromic device. The variation of the transmittance with heating temperature of the photoelectrochromic device was investigated. The results show that the transmittance of the device decreases from 70% (bleached state) to 20% (colored state) under the illumination by 1000W tungsten-iodine lamp for 10min, thus achieving the purpose of adjusting the visible lights.