Vanadium oxide films have been fabricated on Si3N4-film-coated silicon substrates by direct current reactive magnetron sputtering method. Conditions of deposition are optimized making use of parameters such as sputtering time, dc power, oxygen partial pressure and substrate temperature. X-ray diffraction indicates that the film is a mixture of VO2, V2O3, and V3O5. Four-probe measurement shows that the VO x thin film owns high temperature coefficient of resistance (TCR ∼−2.05%/°C) and suitable square resistance 18.40kΩ/□ (measured at 25°C), indicating it is a well candidate material for uncooled IR detectors. In addition, IR absorption in the wavelength of 2–16μm has been characterized. It is worth noting that the films are sputtered at a relatively low temperature of 210°C in a controlled Ar/O2 atmosphere. Compared to traditional craft, this method needs no post-anneal at high temperature (400–500°C).