Abstract: Preperation parameters are studied to get highly pure vanadium dioxide thin films.VO2 thin films are deposited by magnetron sputtering methods.VO2 thin films prepared in different conditions are studied by means of X-ray photoelectron spectroscopy (XPS), constituents of the VO3+,VO4+ and VO5+ in the film are gotten by fitting the XPS peaks with 100% Guassian like curves.Then the thin films are annealed to increase the percentages of the VO4+, the effect of annealing is analyzed.The transmittance at 10.6 μm changed from 74% at 60℃ to 11.93% at 74℃, semiconductor-to-metal phase transition occurs.