This study aimed at the effect of electrolyte filled volume on transmittance and coloration efficiency of the electrochromic device. The device mainly consisted of ITO, WO3 template and electrolyte (PC + LiClO4). The experimental results showed the transmittance of visible light reduced with increasing the electrolyte filled volume. In addition, when the electrolyte filled volume was 100 mm^3, the coloration efficiency could reach the maximum CE, 15.2 cm^2/C.