This study investigates the optoelectronic properties of VO2 thin films in the terahertz (THz) range at different temperatures, with emphasis on the relationship between temperature, conductivity, and transmittance. A 40 nm VO2 film was deposited on a sapphire substrate, and its transmittance and conductivity in the terahertz range were systematically measured using terahertz time-domain spectroscopy (THz-TDS) between 295 and 355 K (22–82 ℃). Results show a significant decrease in transmittance near the phase transition temperature (~ 340 K), corresponding to a transition from the insulating to the metallic state. This is accompanied by a marked increase in conductivity, confirming the link between the phase transition and changes in optical and electrical properties. These findings offer important reference data for designing VO2-based terahertz devices such as modulators and sensors, while enhancing the understanding of the VO2 phase transition mechanism and supporting the development of high-performance terahertz functional devices.