In this paper, using the Mie scattering theory, the mass extinction coefficients and the band mean mass extinction coefficients of the oil fog with the lognormal distribution are calculated in visiblelight band(0.3~0.8μm) and the IR transmission windows(including 3~5μm and 8~14μm). With the study of the relation between the parameters of the particles distributions and the mass extinction coefficients (or the band mean mass extinction coefficients), the mass extinction coefficients or the band mean mass extinction coefficients are maximum when b0 closes to 1 and r0 is near to the extinction (wave band) wavelength. By the experiments, the extinct characteristics of the natural condensate oil (diesel oil) fog is studied. The results show that the natural condensate oil fog has the strongest extinct ability on visiblelight band, and has the feeblest extinct ability on far IR band. The mean particle radius of the natural condensate oil fog approaches the wave length of the visiblelight band. The experiment results are concordance with the theoretical analyzing.