Abstract: Dagang vacuum residue was cut into sixteen fractions with supercritical fluid extraction and fraction (SFEF) instrument. The tailing was degraded by ruthenium ions catalyzed oxidation (RICO) reaction. From this reaction, homologous series of n alkanoic acids, α,ω di n alkanoic acids and benzenepolycarboxylic acids were detected and measured after esterification with diazomethane or phenacyl bromide. Wherein, n alkanoic acids represented aromaticattached n alkyl side chains, α,ω di n alkanoic acids presented the structure features of the polymethylene bridges between two aromaticunits, and those benzenepolycarboxylic acids indicated the major mode of aromatic condensations in the tailing. The products identified in this study show that the structure features of SFEF tailing, especially aromatic condensations mode, are not same as those results reported. Such information is very useful and important for the deep processing and optimizeuse of Dagang vacuum residue.