To　prevent　global　warming,　vigorously　developing　hydrogen　energy　has　become　one　of　research　focuses　of　various　countries　and　regions　in　recent　years.　Hydrogen-fueled　engines　have　been　proven　to　be　a　potential　alternative　to　current　fossil-fueled　engines.　Among　various　engines,　Wankel　rotary　engine　(WRE)　is　praised　for　its　simple　structure　and　excellent　dynamic　characteristics,　which　can　greatly　compensate　for　the　low　specific　-volume　heat　value　of　hydrogen.　However,　hydrogen-fueled　WRE　suffers　from　low　efficiency,　high　NOx　emis-sion　and　severe　knock.　For　methanol-reforming　hydrogen-fueled　ICEs,　CO2　as　the　by-product　can　be　used　as　variant-cooled-EGR　to　improve　ICEs　performance　and　prevent　abnormal　combustion.　Therefore,　this　work　re-searches　the　behavior　of　CO2　on　the　hydrogen-fueled　WRE.　The　work　is　conducted　at　1500　r/min　and　wide-open　throttle.　The　results　show　that　CO2　has　a　significant　influence　on　the　heat　release　process　of　hydrogen-fueled　WRE.　Due　to　this　influence,　when　the　volume　fraction　of　CO2　in　intake　(CO2%)　is　increased　from　0　to　19.28%,　the　brake　thermal　efficiency　can　be　improved　by　8%　with　a　7%　decline　in　power　output.　The　NO　emission　has　two　orders　of　magnitude　of　reduction　with　increasing　CO2%　from　0　to　19.28%..　In　addition,　compared　with　cooled-EGR,　CO2　has　a　better　effect　on　knock　suppression.　If　methanol-reforming　to　produce　hydrogen　becomes　the　mainstream　of　on-board　hydrogen　production　in　the　future,　the　application　of　CO2　is　of　great　significance.