Carbon　materials　with　hierarchical　porous　structure　and　heteroatom-doping　have　gained　extensive　attention　as　promising　electrode　for　supercapacitors.　In　this　study,　we　report　a　facile　approach　which　involves　only　one　step　of　calcination　and　washing　treatment　to　prepare　nitrogen-doped　carbon　material　with　tunable　pore　structure.　This　carbon　material　was　derived　from　chitosan　employing　the　blend　of　potassium　nitrate　and　hexahydrate　magnesium　nitrate　as　the　active　agent.　By　adjusting　the　calcination　temperature　and　active　agents,　the　morphology　and　pore　structure　of　the　material　can　be　effectively　controlled.　By　means　of　this　approach,　the　three-dimensional　hierarchical　porous　carbon　possesses　a　large　specific　surface　area　of　922　m2　g−1,　and　abundant　nitrogen　and　oxygen　functional　groups.　Benefiting　from　these　advantages,　the　final　product　shows　high　specific　capacitance　of　225.3　F　g−1　in　a　three-electrode　system　at　1　A　g−1,　good　cycle　stability　with　88%　capacity　retention　after　10000　cycles　at　5　A　g−1.　Additionally,　the　constructed　symmetric　two-electrode　supercapacitor　shows　remarkable　specific　energy　of　10.46　Wh　kg−1　with　the　specific　power　of　500.08　W　kg−1.　It　also　showed　excellent　electrochemical　performance　in　PVA/KOH　hydrogel　electrolyte　with　70.8　F　g−1　at　the　current　density　of　1　A　g−1.　©　2021　Elsevier　Inc.