The cryogenic spectrometer for the airborne thermal infrared hyperspectral imager (ATHIS) was designed in this paper. In order to detect the spectral recognition capability of the ATHIS, detailed spectral characteristics tests were carried out in the laboratory. The method of CO₂ laser combined with high precision monochromator was proposed to achieve the absolute spectral calibration accuracy of 0.8 nm. Methane gas was tested in the laboratory, and the results show that methane gas could be accurately identified. Twice flight tests of the ATHIS was carried out based on those experiments. The data processing results show that thermal infrared hyperspectral imager can effectively carry out classification and identification of typical urban buildings and effective monitoring of industrial chemical gas emissions. The above preliminary application shows that the ATHIS has excellent spectrum recognition power, and the primary business application prospect. The follow-up instrument will carry out the researches on the enhancement of radiation quantification.