Electrical double layer capacitors(EDLCs)have become increasingly important in energy storage technology.The performances of EDLCs are mainly determined by the electrode materials.[1] Herein,novel 3D hierarchical nitrogen-doped carbon nanocages(hNCNCs)was prepared by in situ MgO template method,which integrate the advantages of large specific surface area,multiscale porous structure,good conductivity,as well as excellent wettability.The synergism of these characteristics ensures the sufficient space for charge storage and the fast transport for ions and electrons.The optimal sample exhibits the state-of-the-art supercapacitive performances with an ultrahigh specific capacitance up to 313 F g?1 at 1 A g?1.The corresponding EDLC delivers the high energy density(10.90 Wh kg?1),power density(22.22 kW kg?1),excellent rate capability and cycling stability.The much better supercapacitive performance of the hNCNCs than that for the undoped hCNCs is attributed to the greatly improved hydrophilicity due to N-doping which effectively increases the ion-accessible surface,facilitates the ion diffusion,thus reduces the charge transfer resistance and ESR of the device.Together with the convenient preparation and low cost,the 3D hierarchical nitrogen-doped carbon nanocages provide us a new kind of top-ranking EDLCs electrode materials with great potential applications.