Abstract: Based on the model of the two phases of grain and grain boundary, the resistivity of the VO₂ film prepared by Ion Beam Enhanced Deposition （IBED） method was studied. The lattice distortionhypothesis and grain boundary tunneling are supposed to simulate the resistivity change of the VO₂ polycrystalline film with temperature. Due to the present of Ar+in interstitial site of VO₂ lattice, some grains begin the semiconductor-to-metal phase transition at 48℃ lower than the phase transi-tion temperature of VO₂ single crystal.