An　effective　B-site　doping　strategy　through　heterovalent　ions　was　developed　to　synthesize　a　series　of　pyrochlore　Pr2Zr1.95X0.05O7+delta　(PZX,　X　=　Mn,　Sc,　Sn,　Nb,　Mo,　Al,　Ga,　In)　for　the　direct　ammonia　solid　oxide　fuel　cell　(DA-SOFC)　cathode.　To　guide　the　design　of　efficient　cathodes　for　DA-SOFC,　we　explore　the　relationships　between　the　ionic　radius/valence　of　dopant　and　electrochemical　performance.　In　view　of　the　energy　matching　and　interaction　between　the　dopant　and　the　host　lattice,　the　substitution　of　trivalent　Sc3+　with　similar　ionic　radius　for　tetravalent　Zr4+　can　greatly　improve　the　oxygen　reduction　reaction　activity　of　Pr2Zr2O7　due　to　the　reduced　bond　energy　of　48f-oxygen　ions　in　octahedral　[ZrO6]　units.　As　a　result,　the　anode-supported　single　cell　Ni-YSZ|YSZ|PZSc-60YSZ　yields　an　output　power　density　of　0.44　and　1.45　Wcm(-2)　at　600　and　800　degrees　C　with　ammonia　fuel,　outperforming　PZX　(X　=　Mn,　Sn,　Nb,　Mo,　Al,　Ga,　In)　and　common　La0.8Sr0.2MnO3　(LSM)-based　DA-SOFC.　The　detailed　characterizations　are　employed　to　gain　insight　into　the　structure-activity　relationship　and　reaction　mechanism.