Designing an efficient catalyst is essential to improve the electrochemical performance for Li-O-2 batteries. In this study, the novel composites of Fe/Fe3C carbon nanofibers (Fe/Fe3C-CNFs) were synthesized via a facile electrospinning method and used as cathode catalysts for Li-O-2 batteries. Owing to their favorable structures and desirable bifunctional catalytic activities, the resulting cathodes with a Fe/Fe3C-CNF catalyst exhibited superior electrochemical performance with high specific capacity, good rate capability and cycle stability. It is revealed that the synergistic effect of the fast kinetics of electron transport provided by the CNF support and the high electro-catalytic activity provided by the Fe/Fe3C composites resulted in the excellent performance for Li-O-2 batteries. The preliminary result manifests that the composites of Fe/Fe3C-CNFs are promising cathode electrocatalysts for Li-O-2 batteries.