A high stable electrochromic device (ECD) based on vanadium pentoxide (V2O5) thin film[1] and a viologen [2](Vio) solution was fabricated and studied.The Ti-doped V2O5 films were prepared by ultrasonic spraying (ULS).The structure of a V2O5-Vio-based ECD can be formulated as (ITO/V2O5/Vio in solution/ITO), and can be switched reversibly between deep blue and colorless states.This complementary ECD shows a high optical contrast of 22 at 608 nm.A maximum transmittance of the ECD at 608 nm can be changed reversibly from 74.73% to 3.31% with the operating potentials of-1.2 V for darkening and 0 V for bleaching.The fabricated device exhibited high transparency and good stability up to 250000 cycles at high temperature of 60 ℃.