Abstract: The developed infrared spectroscopic in situ characterization system under high and low temperature environments combines infrared spectroscopy with high and low temperature in situ infrared system, which provides effective information for in-depth study of high and low temperature in situ infrared reaction mechanism, and provides new technical support for the construction of efficient and stable in situ infrared research. The infrared spectroscopic in situ characterization system under high and low temperature environments provides a low temperature and constant temperature environment for spectral measurement under vacuum or atmospheric pressure through liquid nitrogen refrigeration and heating regulation, and can provide in situ pretreatment or in situ reaction within a certain temperature range of high temperature environment. The infrared spectroscopic in situ characterization system in high and low temperature environments can be applied to the study of any material. It is especially used for gas adsorption studies in liquid nitrogen environment, such as the process capture of reaction intermediates, the studies on weak adsorption of probe molecules, the identification of single-atom catalysts and the adsorption characterization of probe molecules, etc. Therefore, infrared spectroscopic in situ characterization system in high and low temperature environments are extremely high versatility and practical in these fields.