In order to make up for the shortcomings of the existing fire investigation technology, a Fourier transform infrared spectrometer was developed based on infrared remote sensing technology. The equipment is mainly composed of a telemetry probe and a two-dimensional turntable. The telemetry probe is used for the scanning of toxic and harmful gas clouds and the acquisition of infrared spectral data. After data interpolation and filtering, fast Fourier transform, spectral calibration, database spectral format conversion, poison type identification and relative concentration calculation, the remote identification of hazardous toxic gases is realized and the display alarm is performed. In order to verify the feasibility of the research and development equipment in the application of fire investigation, the application effect of Fourier transform infrared spectrometer was measured in a chemical industry park and simulated fire scene. The results show that the developed Fourier transform infrared spectrometer can compare the measured spectrum after pretreatment with the established toxic and harmful gas library, and then mark the range of leaked gas, locate the leak location and determine the leak source. The equipment can not only provide reference guidance for fire fighting and rescue, but also play an active role in determining the scope of investigation, finding the direction of investigation, providing data support and strengthening personal security.