Using V2O5 and MOO3 powders as precursors, a novel preparation method, i.e., the so-called inorganic sol-gel, is developed to synthesize Mo6+-doped vanadium dioxide (VO2) thin films. The structure, valence state, phase transition temperature and magnitude of resistivity change are characterized by x-ray diffraction, x-ray photoelectron spectroscopy and the four-point equipment. The results show that the main chemical composition of doped thin 61ms was VO2, the structure of MoOa in doped thin films did not change, and the phase transition temperature of doped thin Sims was obviously lowered with the increasing MoOs doped concentration, but the magnitude of resistivity change was also decreased. However, so long as MoO3 doped concentration was not more than 5 wt. %, the magnitude of resistivity change of doped thin Glms still reached more 2 orders. The analysis show that MoO3 dissolved in crystal structure of VO2 formed the donor defect MOJ and then reduced the forbidden-band width, which lowered the phase transition temperature. Consequently it was widened applications of the VO2 thin films.