A　series　of　boron-doped　graphene-supported　nanoflower-catalysts　(nf-MnOx/BG)　were　synthesized　using　an　in-　situ　method　to　boost　intrinsic　catalytic　performance.　The　regulation　of　catalyst　structure,　morphology,　and　active　sites　was　systematically　researched　to　explore　the　promoting　factors　of　catalytic　activity.　The　prepared　nf-MnOx/　BG-3　catalyst　achieves　superior　NH3-SCR　performance　throughout　the　test　process　(＞=　90%　NOx　conversion　at　the　temperature　ranging　from　140　to　280　degrees　C),　comparable　to　the　current　mainstream　graphene-based　catalyst.　The　ratios　of　O　alpha/(O　alpha　+　O　beta)　and　Mn4+/Mn3+are　effectively　increased　by　boron　atom　doping,　which　is　strongly　associated　with　excellent　catalytic　deNOx　efficiency.　Meanwhile,　the　boron　sites　with　unpaired　electronic　structures　accelerate　the　reaction　of　fast-SCR　by　promoting　oxidation　and　adsorption　of　nitrogen　oxide　species.　Interestingly,　the　boron　sites　can　be　used　as　an　additional　Lewis　acid　and　adsorbed　NO2　site　to　participate　in　the　low-temperature　SCR　reaction　and　effectively　improve　the　low-temperature　activity.