A　theoretical　study　on　the　oxygen　reduction　mechanism　catalyzed　by　metal　polyaniline　is　investigated　in　detail　by　means　of　density　functional　theory.　In　the　oxygen　reduction　process,　we　find　that　-OH,　not　H2O2,　is　the　reaction　intermediate.　The　catalytic　activities　for　the　studied　models　decrease　in　the　sequence　CoFe-PANI　＞　Fe-PANI　(FeFe-PANI)　＞　Co-PANI.　This　is　due　to　a　synergistic　effect　between　heterogeneous　metal　atoms　in　CoFe-PANI,　which　facilitates　additional　electron　donation　from　the　active　sites　to　the　adsorbed　oxygen　reduction　intermediates.　The　doping　with　cobalt　may　also　decrease　the　HOMO-LUMO　gap　in　CoFe-PANI,　making　it　more　active.