Abstract: The characteristics of Infra -Red spectra for the upper Triassic coal series in the Sichuan Basin are studied.Based on the analysis on the data from more than 20 wells,three absorption peaks associated respectively with structures of alkane-chain,benzene ring and radicals of hetero-atoms have been distinguished,and it reveals the characteristics of the upper Triassic source rocks,coal and crude oil constitutions.In addition,the study provides basis for the determinations of sedimentary environment,organic types and oil gen-erating potential.