Vanadium dioxide thin films undergo phase transition metal phase to semi-conducting phase at 68℃. With the transition, reversible saltation of the electrical and optical properties occurs, turning the thin films into a ideal functional material for producing electrical, optical devices, such as micro-bolometers, memorizers, photo switches and etc. By thin films doping technologies, the phase-transition temperature can be reduced to room temperature. Transmission coefficient of phase-transition coating will change while temperature changes. It is particularly effective in smart glass windows. And it is significant for energy saving.