In　recent　years,　ammonia　attracts　much　attention　from　researchers　as　a　carbon-free　energy　carrier,　but　low　reactivity　hinders　the　direct　use　of　ammonia　in　combustion　applications.　In　this　study,　several　essential　combustion　properties　were　numerically　studied　to　explore　the　possibility　of　using　oxygen　enrichment　to　enhance　ammonia　combustion.　Fuel　lean　and　rich　oxygen-enriched　ammonia　flame　was　simulated　by　planar　flame　and　one-dimensional　spherical　flame　under　various　oxygen　fractions.　Results　show　that　increasing　oxygen　content　substantially　increases　the　laminar　burning　velocity　and　mixture　heating　value　but　decreases　the　burned　gas　Markstein　length　and　combustion　efficiency.　NO　is　the　major　NOx　emission,　which　rises　with　oxygen　content　for　rich　combustion　but　nonmonotonically　changes　for　lean　combustion　due　to　the　start-up　of　NO　post-reduction　at　high　temperature.　The　chemical　effect　of　N-2　possesses　negligible　influences　on　most　of　the　flame　properties,　except　for　weakening　the　NO　post-reduction　in　the　burned　gas.　Competition　between　the　increase　in　flame　temperature　and　the　decrease　in　N-2　content　leads　to　the　maximum　chemical　effect　of　N-2　occurring　at　the　oxygen　fraction　of　0.6.　In　summary,　oxygen　enrichment　can　be　an　effective　option　to　solve　the　problems　impeding　ammonia　fuelization.