As a new type of reversible phase change material, vanadium dioxide (VO2) has shown great potential in development with the regulation of its phase change temperature (TMIT) and were extensively studied. The experiment in this study focuses on exploring the effect of germanium ions on TMIT of VO2 thin films and trying to explain the internal mechanism. A series of VO2 films containing different ratios of germanium ions were deposited on polished alumina sheets. The characterization results show that germanium ions contribute to increasing TMIT (maximum TMIT is 84.7 ℃). The main reason for this increase is that germanium ion enhances the stability of monoclinic V-V dimer by increasing the stability of monoclinic V-V dimer, which makes the transition from low-temperature monoclinic state to tetragonal rutile state more difficult.