Electrochromic (EC) devices possess the advantages of low operating voltage, many stable states, non power consumption under static state, low power consumption for color change and continuously adjustable transmittance/reflectance and so on. WO3 electrochromic devices have problems such as long response time and low optical modulation amplitude. In order to further shorten the response time, this article uses WO3 film as the color changing layer to prepare electrochromic devices. The effect of different argon-oxygen flow ratios on the WO3 film deposition and the response time of EC devices are studied. In order to further shorten response time, we used the Ag-WO3 composite layer as the color-changing layer for the EC devices. The results show, when the argon-oxygen flow ratio is at 50∶50, the response time of the EC devices prepared only by the WO3 film is the shortest. The coloring time and the fading response time are 2127 s and 11.68 s respectively. When the EC devices were using the Ag-WO3 composite film as the color-changing layer and the Ag layer thickness is 6 nm, the two response times are the shortest. The coloring time and the fading response time are 1271 s and 7.89 s respectively. The response time of the EC devices prepared by WO3 film is influenced on different argon-oxygen flow ratios. Moreover, the response time of the EC devices prepared by Ag-WO3 composite film is significantly shorter than that of the devices made by WO3 film. However, when the Ag layer thickness increases, the response time of the devices also increases.