VO₂ thin films were prepared by DC magnetron sputtering combined with oxidational annealed on Si substrate. SEM, XRD and XPS were employed to study the section, crystal composition, and valence of VO₂ thin films from various aspects, and the infrared transmission properties was analyzed by FTIR. The results of analysis show that, a better crystal orientation of monoclinic rutile structure VO₂ (011) crystal can be prepared through the method of DC magnetron sputtering combined with oxidational annealing, and the oxidational annealing is beneficial to the growing of VO₂ grain and compactness of thin films. The VO₂ thin films possesse a obvious phase transition properties, the transition temperature is 60.5 ℃, and the range of the change of infrared transmission rate at 3-5 μm and 8-12 μm has reached to 99.5%. The VO₂ thin films have achieved the function of switch in infrared transmission, which can be an ideal material for the research in protecting infrared detector of laser attacking, and provides references for further in-depth study on oxidational annealing.