Abstract: Aiming at the problems of water vapor interference and low reliability of carbon dioxide sensor in coal mine, a laser carbon dioxide sensor based on TDLAS is designed on the basis of infrared carbon dioxide sensor.The principle of sensor technology and the design of hardware and software are introduced in detail.The sensor extracts the second harmonic of the spectral signal after gas absorption, calculates the amplitude of signal attenuation, and deduces the concentration of the gas to be measured according to the formula.The experimental results show that compared with infrared sensor, laser carbon dioxide sensor has higher reliability, stronger anti-interference ability, can effectively avoid water vapor interference, and has a wide range of application prospects and economic benefits.