Ammonia　is　considered　as　a　carbon-free　alternative　fuel　and　hydrogen　carrier　to　realize　green　and　renewable　energy　conversion,　but　the　oxidation　mechanism　of　NH3　still　needs　to　be　improved　and　validated　by　more　experimental　data.　In　this　study,　the　laminar　burning　velocity　(LBV)　was　measured　in　a　constant　volume　vessel　at　various　equivalence　ratios,　initial　temperatures,　and　oxygen　fractions　up　to　undiluted　condition.　Thirteen　latest　NH3　kinetics　mechanisms　were　collected　and　compared　with　each　other　and　the　experiments.　Results　showed　that　large　discrepancies　of　predictions　presented　between　different　mechanisms.　The　maximum　LBV　of　undiluted　NH3/O-2　mixtures　could　reach　125.05　cm/s.　The　maximum　predicted　LBV　of　NH3/O-2　is　nearly　two　times　higher　than　the　minimum　one　for　NH3/O-2　mixtures.　The　reduced　Okafor　(2019)　and　Zhang　(2017)　mechanism　gave　the　best　agreement　with　experiments　for　lean　and　rich　mixtures,　respectively.　Sensitivity　analysis　of　rate　constant,　species　thermal,　and　transport　parameters　were　adopted　to　identify　the　critical　reactions　and　species　in　the　premixed　flame.　It　was　found　that　because　of　the　coupled　nature　of　the　properties　mentioned　above　in　the　premixed　flame,　the　species　involved　in　the　essential　reactions　also　exhibit　substantial　thermal　and　transport　sensitivities.