Fourier transform infrared spectroscopy (FTIR) can be used for the continuously on-line quantitative determination of the concentrations of several gas components in smoke gas. The process of acquiring accurate calibration of spectra is one of the most important steps in the quantitative analysis. In the present paper, a novel calibration technique was proposed and evaluated by the results of CO and HCl. Data obtained by this new technique were compared to those of conventional concentration-based calibration. The results showed that this calibration technique is feasible, and its reliability and validity were also confirmed. Further more, it has several other advantages, which will also be discussed here. Finally, the calibration problem that the substances are liquid at ambient temperature was solved by this technique.