Passive Fourier-transform infrared (Passive-FTIR) spectroscopy allows identification of the air pollution. However, information about the position and the distribution of pollution gas is essential for the detection and early warning in the case of the release of a hazardous cloud. In this work, a Scanning Passive FTIR Remote Sensing System, which is composed of an interferometer, a video system, a scanning system and a computer has been developed. The system control software is programmed with LabVIEW. The concentration retrieval algorithm for the passive FTIR remote measurement is presented to get concentration path length of the pollution gas. The results are visualized by a video image, and overlaid by false color concentration distribution image. The validation experiment shows that the system is stable and effective. It has a good prospect in detecting pollution gas distribution.