The red V2O5 sol was prepared by facile alternating stirring and ultrasonic dispersion route. A V2O5 film fabricated on ITO-PET by electrophoresis method was used to demonstrate a flexible electrochromic device. The effects of applied voltage and electrophoresis time for V2O5films were investigated in detail. When the electrophoresis time was kept 30 s, the applied voltage was above 3 V to deposit uniform V2O5-PET film. The electrophoresis time could more significantly regulate the deposition of V2O5 on ITO-PET film. A flexible electrochromic device with “sandwich” structure was fabricated using V2O5 film, and its electrochromic performance of the device was evaluated. The flexible V2O5 electrochromic devices show the multicolor electrochromic performance of yellow, yellow-green, green and orange-red. The coloration efficiency values of V2O5 devices were 21.6 cm2C[Formula: see text] (from initial yellow to green) and 26.9 cm2C[Formula: see text] (from green to orange-red), respectively, and the highest transmittance modulation range was 51% at 741 nm. The work provided a facile and green method for fabrication of flexible V2O5 electrochromic device.