Abstract: The Vario EL Ⅲ element analyzer was applied to the determination of C,H and N in multi-fluoro and perfluoro organic compounds.Mixture of granular MgO and Ag2WO4 was filled in the high temperature zone of the combustion tube acting as catalytic oxidant,to overcome the interferences of fluorine,halogen and sulfur simultaneously.In the analysis of perfluoro-compounds,cataly oxidants WO3 and V2O5 were added directly to the sample and wrapped in the “tin boat” which was combusted and its contents of C,H and N determined.