High refractive index of the substrate material often leads to serious reflection on the surface of infrared optical elements, which will greatly reduce the transmittance of infrared light. To maximize the transmission of infrared light, antireflection (AR) film needs to be plated on the surface of infrared substrate. Sol-gel technology is an effective method for preparing high temperature resistant film. At present, there have been many reports on the preparation of AR film in visible light, however, it is still a challenge to prepare AR film working in infrared band by sol-gel method.