Remote sensing spectrometers were widely used in the fields such as spectral measure and trace gas supervision in atmosphere. The instrument response functions should be measured to eliminate the effect of the spectrometer. The instrument response functions of MCT detector and InSb detector in BLUKER TENSOR 37 passive FTIR spectrometer were measured in the present paper. The instrument response functions and background functions were offered with different temperature interval. The instrument response functions of MCT detector increased with temperature, but it was the reverse for InSb detector. The background functions of InSb detector increased with temperature, and the reverse for MCT detector.