Boron-containing　compounds　have　been　discovered　as　a　kind　of　promising　metal-free　catalysts　for　oxidative　dehydrogenation　(ODH)　of　alkanes.　Herein,　we　provide　a　simple　method　to　synthesize　a　series　of　BCN　catalysts　with　tunable　carbon　contents.　We　reveal　that　incorporating　appropriate　amounts　of　carbon　into　the　hexagonal　boron　nitride　(h-BN)　structure　can　significantly　increase　the　surface　area　and　lead　to　remarkable　enhanced　catalytic　conversion.　The　best-performing　catalyst　shows　82.3%　propylene　selectivity　and　93.8%　olefin　selectivity　at　propane　conversion　of　18.5%.　Systematic　study　indicates　that　the　carbon　doping　can　derive　BN　with　a　large　number　of　defective　sites,　which　are　prone　to　form　reactive　boron-oxygen　species　during　activation.　The　excess　carbon　inclusion,　however,　results　in　a　decreased　catalytic　conversion,　originated　from　catalyst　decomposition　and　sintering.　In　situ　transmission　electron　microscopy　(TEM)　performed　under　activation　and　catalytic　reaction　conditions　shows　the　dynamic　process　of　gas-phase　induced　structural/compositional　transformations,　providing　direct　insights　into　the　origins　of　catalytic　deactivation.　©　2021　Elsevier　B.V.