Carbon dioxide gas sensor is widely used, which benefits from its efficient and practical operation principle. For carbon dioxide gas molecules, the molecular selective absorption theory is mainly used, and the gas concentration can be measured according to the absorption intensity of light. Every substance has its characteristic bright line spectrum and its corresponding absorption spectrum, and the same is true of carbon dioxide gas molecules. The vibration of the lattice of ceramic materials and hinder the movement of electrons. When the temperature rises, the lattice vibration is strengthened and the amplitude is increased, and the effect of blocking electrons is enhanced. At this time, we can know according to the selective absorption theory of gas, and when the emission wavelength of the light source is consistent with the absorption wavelength of the gas, the phenomenon of resonance absorption will occur, and its absorption intensity is related to the concentration of the gas, we can directly measure the concentration of the gas after measuring the absorption intensity of light.