SnO2 buffer layers with different thicknesses were prepared on silicon substrate by electron beam evaporation, and their influence on the microstructure, phase composition and phase transformation properties of the upper vanadium oxide films deposited by magnetron sputtering were investigated. Experimental results show that the lattice of tetragonal-rutile structure SnO2 matches well with that of vanadium oxide films, leading to the thin films contains more V4+. When the thickness of SnO2 buffer layer increases, accompanied by the appearance of more homogeneous sizes of SnO2 crystallite, larger grain sizes, narrower thermal hysteresis loops and sharper phase transition can be observed for the deposited VO2 films. Accordingly, this work indicates that the addition of SnO2 buffer layer with optimal thickness is beneficial to the growth of high-quality VO2 films with excellent phase transition performance.