The reasons of error occurred in measuring Mid-IR spectral radiant intensity of exhaust system with Fourier transform infrared(FTIR) spectrometer was discussed through theoretical analysis and experimental research.A simple and efficient measurement method was also planned to measure the spectral radiant intensity of a blackbody and a hot plume.The results show that Mid-IR spectral radiant intensity of exhaust system could be measured effectively by this method

thus offering a high value of engineering practicability.