Describes the main spectrometric methods of analysis combustion propane-air mixture in the presence of nonequilibrium longitudinal electric discharge in supersonic air flow are considered. The description of the experimental setup are presented. The spectra of vibrational-rotational states of diatomic molecules dicarbon and cyanide are analyzed by three methods: graphic method, method of relative intensities (method of Ornstein) and with unresolved structure of the spectrum. Some conclusions about their practical applicability are reported.