Laser interference can cause interference such as saturation and glare to thermal imager, it seriously affects the image quality. Vanadium dioxide is a phase change material, which has high transmission of infrared radiation at low temperature semiconductor state. In the high temperature metallic state, vanadium dioxide has highly reflectance of infrared radiation. This characteristic can be used to protect infrared thermal imager from laser interference. Self-motivated phase transition vanadium dioxide thin films were prepared by molecular beam epitaxial method, and the transmittance of thin films to mid-infrared laser was measured by an experimental device. The transmittance of the film in semiconductor state is 0. 693 and 0. 069 in metallic state at 3. 525 μm wavelength. An experiment using the vanadium dioxide thin film to protect the thermal image from the middle infrared laser interfering was done. The experimental results show that when the vanadium dioxide film is semiconductor state, most of the incident laser energy can transmit the vanadium dioxide film, which will cause serious interference to the thermal imager. When vanadium dioxide film is in metallic state, most of the incident laser energy is attenuated, and the interference degree of laser to the thermal imager is greatly reduced. Vanadium dioxide thin film can be used to protect thermal imager from laser interference.