The low cost nanostructure thermochromic energy-saving thin films are fabricated by magnetron sputtering deposition at room temperature and oxidation in air atomsphere. The film properties are studied through SEM, XRD, Raman spectroscopy and infrared spectrum analyzer. The relation between the oxidation annealing and microstructure and infrared switching characteristics of VO2 thin films with temperature are analyzed. The major factors which affect the film properties such as the grain size, crystal lattice structure, composition, thermal hysteresis and infrared transmittance and their control methods are obtained. The optimal processing parameters are used to fabricate VO2 nanostructure thermochromic energy-saving thin films on glass with high energy efficiency. The average grain size of VO2 nanocrystals is about 45 nm, calculated by the correlation equation based on XRD and Raman spectrometer. The measured results shows that the infrared light transmittance at 2.5 μm is more than 50%, the phase transition temperature is 39 ℃, visible light transmittance is about 53%, and the VO2 nanostructure energy-saving thin film have good thermochromic properties.