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Carbon-based materials have always been a hot issue of research as important electrode materials for supercapacitors. Their capacitance characteristics depend on specific surface area, pore size distribution, and chemical composition etc. In this report, we utilize sodium citrate as a carbon source and melamine and urea as nitrogen sources. We prepared two types of nitrogen-doped hierarchical porous carbons using a simple and environmentally friendly method for supercapacitors in an aqueous solution containing 6 mol/L KOH. The results show, when melamine was used as a nitrogen source, benefit from a larger BET surface area of 819.5463 m2/g, and higher nitrogen content 4.14% show a higher specific capacitance characteristics 383F g−1 at 0.3A g−1 and high capacity retention of 99.6% after 10,000 cycles compared with the product of urea as a nitrogen source.