Ammonia　(NH3)　is　a　carbon-free　Hydrogen　carrier　with　the　advantages　of　high　volumetric　energy　density,　developed　infrastructure,　as　well　as　easy　and　safe　storage.　The　coupling　of　NH3　catalytic　decomposition　with　electrochemical　oxidation　in　an　anode　of　solid　oxide　fuel　cells　leads　to　the　field　of　direct　Ammonia-fueled　solid　oxide　fuel　cell.　However,　the　related　coupling　mechanism　needs　clarification.　In　the　present　study,　by　developing　a　mechanistic　model　and　a　library　of　elementary　reaction　kinetics,　we　attempt　to　have　an　overview　on　the　synergism　of　heterogeneous　reactions,　charge-transfer　reactions,　bulk　diffusion,　and　charge-transfer　processes　of　direct　Ammonia-fueled　solid　oxide　fuel　cell.　We　describe　charge-transfer　reactions　based　on　hydrogen　spillover　mechanism　as　well　as　oxygen　spillover　mechanism,　and　find　that　only　the　hydrogen　spillover　mechanism　fits　with　experimental　data.　With　this　validated　model,　we　identify　the　rate-determining　steps　as　well　as　the　main　surface　species　in　H-2-fueled　and　NH3-fueled　solid　oxide　fuel　cells.　We　define　the　region　of　NH3　catalytic　decomposition　and　that　of　electrochemical　oxidation　to　quantify　the　coupling　within　the　anode.　Based　on　the　quantification　results,　we　study　the　effects　of　temperature　and　content　of　inlet　NH3　on　cell　performance.