Abstract: Passive dynamic FTIR spectrometer can be used for the spectral analysis of environmental radiation, and infrared signal detection plays an important role in spectrometry. Based on the design concept of circuit, it requires high signal to noise ratio (SNR), high sensitivity, small temperature drift and strong antijamming capability. Using a filtered power supply, and a high-speed, low-noise and high-precision operational amplifier, a circuit was designed for IR signal detection. The infrared spectrometer with the IR signal detection circuit was used to sense the atmosphere remotely, and the experimental results were analyzed and discussed. Experimental results show that the detection circuit is operated with good stability, high SNR, and high accuracy, which enables the IR remote sensing of atmospheric environment.