Vanadium oxide thin film was deposited on sapphire by RF magnetron sputtering. The XRD measurement result shows that the thin film is mainly composed of polycrystalline vanadium dioxide. The resistance of the thin film and its optical reflectivity at five different wavelengths were measured simultaneously during the semiconductor-metal phase transition. While both resistance and reflectivity measurements show reproducible hysteresis loops, they have quite different appearance. The optical phase transitions of VO2 at different points are almost the same, thus proving that the sample is uniform.