Nitrogen　and　boron　co-doped　activated　carbon　(BKACS)　was　synthesized　through　the　carbonization,　KOH　activation　and　subsequently　hydrothermal　doping　reaction　process　with　chitosan　as　the　renewable　carbon　source.　The　prepared　samples　were　characterized　by　XRD,　SEM,　Raman,　XPS　and　BET　for　their　structure,　morphology,　specific　surface　area　and　elemental　composition,　respectively.　The　obtained　BKACS　has　a　specific　surface　area　of　1129.6　m(2)　g(-1),　with　high　conductivity　and　capacitive　character.　The　BKACS　was　applied　as　the　electrode　material　to　fabricate　the　electrochemical　double-layer　supercapacitor.　The　supercapacitor　performed　a　high　specific　capacitance　of　316　F　g(-1)　at　0.2　A　g(-1)　in　a　three-electrode　system　in　the　6　M　KOH　electrolyte　and　excellent　cycling　stability　with　a　capacitance　retention　of　94.08%　after　10,000　cycles　at　10　A　g(-1).　The　attractive　supercapacitor　performance　of　the　BKACS　material　has　the　high　power　density,　excellent　cycling　life,　and　environmental　friendliness,　making　it　potentially　a　promising　replaceable　function　for　future　energy　storing　device.