Vanadium dioxide is a kind of material with reversible phase transition from insulating state to metallic state. It is widely used in optical devices and information technology. In this paper, the phase transition process of silicon-based vanadium dioxide is studied and analyzed by terahertz spectroscopy and array imaging technology. Firstly, the transmission spectra and reflection spectra of the whole sample in the 2.5~20.0 THz region are obtained by using the Fourier transform spectrometer. The analysis shows that the temperature range of phase transition of silicon-based vanadium dioxide is from334 K to 341 K, and the corresponding temperature difference is 7 K. It is obtained that the transmittance of the sample to 4.3 THz radiation changes more than 40% and the reflectivity changes close to 30% after phase transition; then, a set of 4.3 THz array imaging system is utilized to measure the THz images of the whole sample before and after phase transition. When the material changes from metal state to insulating state, the transmittance of 4.3 THz light increases from 6.7% to 50.7%, and the transmittance change is 44%, which is near to the results of Fourier transform spectra at 4.3 THz. The above research results provide good experimental data support for the transmission modulation and reflection modulation of silicon-based vanadium dioxide for electromagnetic radiation above 2.5 THz.