The individual WO3 film and a series of Hierarchical structure WO3/TiO2 complex films were fabricated by Radio Frequency (RF) magnetron sputtering. The influence of TiO2 thickness on electrochromic properties of WO3 thin films is investigated. The capability for accommodating H+, the diffusion coefficient (D) value of H+ and the life-time or cycle stability of WO3 films were effectively enhanced by appropriate thickness (60 nm) of TiO2 coated on WO3.