The vanadium oxide thin film with high quality was prepared on c-Al2O3 substrate for the first time by magnetron sputtering with rapid thermal process(RTP). Firstly, the surface particle size of the film was uniform, the surface root mean square roughness was about 16.75 nm, the major components of the film were VO2 and V2O5, V4+ content was about 78.59%. The prepared vanadium oxide thin films had the stable property of thermal-excited phase transition; Secondly, the terahertz transmission modulation was characterized by terahertz time-domain spectroscopy system(THz-TDS). The result indicated that the transmission ratios of the film increased with increasing optical excitation power; Finally, the amplitudes of the THz waves for vanadium oxide without any obvious fluctuation after the optimized process conditions of preparation and transmission ratios were nearly stable within repeated testing by in-site test, could be widely used for THz devices such as modulators and switches.