A systematic investigation of the nanoscale conduction behavior of vanadium dioxide (VO2) films deposited on aluminum oxide (Al2O3) substrates, using conductive atomic force microscopy, is presented. Aside from the macroscale resistance-temperature characteristics, which show a steep insulator-metal transition at the transition point Tm ∼ 68 °C, our experiments demonstrate a coexistence of nanoscale high-conduction and low-conduction phases over a broad temperature window (50 K range) across the Tm. In addition, the area (volume) fraction of the high-conduction phase increases with increasing temperature across the transition point. The current-voltage data obtained on a nanoscale indicate that the high-conduction phase is not a good metal. When the temperature increased across the Tm, the probed charge transport behavior of the high-conduction phase is found to change from a mechanism dominated by space-charge limited current to a mechanism dominated by Schottky emission.