A novel inversion method of optical constants of diesel fuel that is one of semitransparent liquid was developed based on spectral transmittance radio inversion calculation of optical cell with glass-liquid fuel-glass configuration, which was validated by measured the optical constants of water. The measurements of transmittance spectrogram of optical cell filled with diesel fuel in the infrared wavelength 2~15 μm at normal incidence were investigated by Bruke V70 FTIR spectrometer. The optical constants and thermal radiative physcial parameters of diesel fuel were achieved. The results show that, (1) The optical constants of water determined by the new method (IDTM) have good agreement with previously data sets. (2) The optical constants calculation precision of the IDTM is similar with MCDTM, which is higher than SODTM and SDTM. (3) The transmittance capability of diesel fuel in the infrared wavelength 2~15 μm are weak, and there exist five absorption peaks, which are respectively 2.4, 3.4, 6.2, 7.3 and 13.8 μm. (4) The spectral selectivity of optical constants and thermal radiative physcial parameters of diesel fuel are stronger, whose values are urgently varied with different wavelenths.