Ammonia　has　the　advantages　of　being　easy　to　liquefy,　easy　to　store,　and　having　a　high　hydrogen　content　of　17.3　wt%,　which　can　be　produced　without　COx　through　an　ammonia　decomposition　using　an　appropriate　catalyst.　In　this　paper,　a　series　of　FeCr　bimetallic　oxide　nanocatalysts　with　a　uniform　morphology　and　regulated　composition　were　synthesized　by　the　urea　two-step　hydrolysis　method,　which　exhibited　the　high-performance　decomposition　of　ammonia.　The　effects　of　different　FeCr　metal　ratios　on　the　catalyst　particle　size,　morphology,　and　crystal　phase　were　investigated.　The　Fe0.75Cr0.25　sample　exhibited　the　highest　catalytic　activity,　with　an　ammonia　conversion　of　nearly　100%　at　650　degrees　C.　The　dual　metal　catalysts　clearly　outperformed　the　single　metal　samples　in　terms　of　their　catalytic　performance.　Besides　XRD,　XPS,　and　SEM　being　used　as　the　means　of　the　conventional　characterization,　the　local　structural　changes　of　the　FeCr　metal　oxide　catalysts　in　the　catalytic　ammonia　decomposition　were　investigated　by　XAFS.　It　was　determined　that　the　Fe　metal　and　FeNx　of　the　bcc　structure　were　the　active　species　of　the　ammonia-decomposing　catalyst.　The　addition　of　Cr　successfully　prevented　the　Fe　from　sintering　at　high　temperatures,　which　is　more　favorable　for　the　formation　of　stable　metal　nitrides,　promoting　the　continuous　decomposition　of　ammonia　and　improving　the　decomposition　activity　of　the　ammonia.　This　work　reveals　the　internal　relationship　between　the　phase　and　structural　changes　and　their　catalytic　activity,　identifies　the　active　catalytic　phase,　thus　guiding　the　design　and　synthesis　of　catalysts　for　ammonia　decomposition,　and　excavates　the　application　value　of　transition-metal-based　nanocomposites　in　industrial　catalysis.