In this work, porous decatungstate-TiO2 composite thin film has been prepared by the electrodeposition method. The advantages of decatungstate as electrochromic material are discussed and the electrochromic performances of the composite film have also been systematically investigated. The transmittance decreased from 98.0% down to 50.8% at the wavelength of 550 nm under an applied potential of -0.8 V. Good reversibility and reproducibility also can be observed in the composite electrochromic film. The porous structure of the composite film not only provides a large surface area for loading W-10 polyanions but is also beneficial for the fast diffusion of H+, which results in high electrochromic performances. (C) 2017 Elsevier B.V. All rights reserved.