The interferogram acquisition principle and process of infrared Fourier spectrometers were presented. On the basis of MATLAB, modeling and calculation of the characteristics of interferograms were carried out by combining numerical integration with discrete Fourier transform for the first time. The interferograms corresponding to different temperature blackbody radiation were obtained and their direct component, maximum value and relative minimum value were analyzed. The linear relationship between the relative minimum value and the direct component was given quantitatively and was verified by comparing experimental data. The background noise of an atmospheric vertical detector system was analyzed in terms of the characteristics of interferograms for the first time in China. Then, the feasibility of using the subtraction circuit in CTIA to improve the dynamic range of the detector was analyzed. The result showed that the method was not feasible.