Optical systems and photoelectric devices are easily damaged under high energy laser irradiation. Therefore, the laser protection of photoelectric devices is critical. Vanadium dioxide has unique phase transition characteristics, which can realize a reversible semiconductor-metal phase transition under heat and light stimulation. Simultaneously, vanadium dioxide has a low phase transition threshold, high damage threshold, and short response time, which are conducive to laser protection. To solve the problem of low infrared transmittance of a single-layer vanadium dioxide film in the semiconductor phase, a multilayer composite film system is designed and optimized. The photothermal coupling characteristics of the vanadium dioxide phase transition induced by laser are then analyzed using a finite element method, and variations in the vanadium dioxide refractive index with temperature are derived, where the transmittance of multilayer composite films is inverted according to these variations. The results show that the designed multilayer film has a transmittance and infrared switching rate of 66.81% and 75.43%, respectively, at a wavelength of 3 μm. This study expands the application of vanadium dioxide film in the field of laser protection in the middle infrared field.