In order to monitor and identify chemical fires quickly, a flame spectrum test platform is established based on FTIR spectrometer. The flame spectrums of two nitrogenous chemicals (acrylonitrile and acetonitrile) and the anhydrous ethanol are detected and analyzed in the indoor sealing condition, and the spectral range is 600-8000 cm^-1. The results show that the order of molecular radiation intensity in the same combustion conditions is acrylonitrile, acetonitrile and anhydrous ethanol from large to small. This is because acrylonitrile and acetonitrile produces more H₂O molecules than the anhydrous ethanol when combusting, and a lot of carbon black is produced by the combustion of acrylonitrile. The flame spectrums of acrylonitrile, acetonitrile and absolute ethanol are substantially similar after denoising and smoothing, but there are unique differences of high-temperature nitrogenous gas at the wave numbers of 1650 cm^-1, 1830 cm^-1, 2857 cm^-1 and 3750 cm^-1. The experiment conclusion shows that the flame spectrum radiation detection of nitrogenous chemicals by using FTIR spectrometer can enhance the ability of rapid monitoring and identification of chemical fires in China.