The　work　showed　a　novel　amperometric　NH3　sensor　based　on　SrM2O4　(M　=　Sm,　La,　Gd,　Y)　with　CaFe2O4　type　structural　sensing　electrode.　A　distinct　B-site　strategy　was　developed　to　prepare　a　series　of　semiconductor　oxides　SrM2O4　(M　=　Sm,　La,　Gd,　Y)　to　establish　the　relationships　between　the　band　structure　and　sensing　properties　of　the　optimized　sensing　electrode.　The　structural　analyses　carried　out　by　X-ray　diffraction,　scanning　electron　microscopy　and　Mott-Schottky　curves　confirm　that　four　metal　oxides　SrM2O4　(M　=　Sm,　La,　Gd,　Y)　are　all　n-type　semiconductors,　and　a　preferential　sensing　mechanism　of　NH3　sensor　was　proposed　by　the　combination　of　mass　spectrometry　track.　The　electrochemical　results　indicate　that　NH3　sensing　properties　are　closely　related　to　the　band　structure　of　the　metal　semiconductor　oxides.　Compared　with　the　conduction　band　obtained　from　Mott-Schottky　curves,　it　is　the　most　negative　for　SrM2O4　sensing　electrode,　suggesting　that　electrons　are　easier　to　overcome　energy　barriers　over　SrM2O4.　Consequently,　the　NH3　sensor　with　SrM2O4　sensing　electrode　exhibits　high　sensitivity,　quicker　response/recovery　speed,　excellent　selectivity　and　stability　compared　to　other　three　sensors,　exhibiting　a　great　application　prospects　for　SrM2O4　sensing　electrode　used　in　the　automotive　equipments.