Three-dimensional macroporous tungsten trioxide (WO3) was electrochemically prepared by using the polystyrene opal as a template. The photonic stop band of the porous WO3 film could be changed when the WO3 was intercalated with lithium cation by the electrochemical method. The change of the stop band was attributed to the chan-e of the refractive indices accompanied with the electrochromism Of WO3.