Abstract: In order to improve electrochromic properties of tungstic oxide（WO<SUB>3</SUB>）thin film,WO<SUB>3 </SUB>electrochromic thin film doped with polyvinyl alcohol （PVA） was prepared by peroxopolytungstic acid sol-gel method.Microstructure of the film was observed by metallographic microscope.Light transmittance and characteristics of cyclic voltammetry of the film were investigated by UVPC and CHI,relatively.Results indicated that addition of a certain amount of PVA can make the film structure more even and chromatism more uniform;adjustable range of color change increased while the difference value of light transmittances in colored-and bleached-states was more than 60%;electrochromic reversibility and spectral properties were both improved comparing with those without doping.&nbsp;&nbsp;