Annealing experiments are performed at 450 ℃ in N2 atmosphere for different time on vanadium oxide films prepared by RF magnetron sputtering. Changes in surface morphology, electrical, structural properties and chemical composition are studied. From resistance-temperature (R-T) measurement and calculation, it is found that both R and temperature coefficient of resistance (TCR) of the films are increased after annealing. From scanning electron microscope (SEM) and (AFM) atomic force microscope images, it is observed that both grain size and surface roughness are aggrandized greatly after annealing. X-ray diffraction (XRD) analysis shows that the as-sputtered film is almost amorphous while new phases V2O5(0 0 1), VO2(0 1 1, 1 -1 0) and V2O3(1 1 3) appear in the annealed films. X-ray photo-electronic spectrum (XPS) quantitative analysis indicates that the annealed films are oxidized possibly due to adsorbed oxygen to lattice oxygen transition.