Objective To improve the electrochemical performance of graphene films for supercapacitors. Methods Flexible nitrogen-doped graphene (N-doped graphene) films with porous structure were synthesized by hydrothermal and pyrolysis methods. The structure of the N-doped graphene films were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and isotherms. The electrochemical capacitance of N-doped graphene films was examined by three-electrode system test cyclic voltammetry and galvanostatic charge-discharge methods. Results The experiments indicated that the flexible N-doped graphene films retained the folded and transparent characteristics of graphene oxide, and formed a three-dimensional porous structure as well. The surface area of N-doped grapheme was measured to be 280. 78 m2 / g by the nitrogen adsorption-desorption test. The specific discharge capacitance for the material was 169 F/ g in 1. 0 mol/ L NaSO4 solution when the current density was 0. 1 A/ g. Conclusion The doping of nitrogen atoms and the porous structure of the flexible N-doped graphene films could effectively improve the supercapacitor performance of the graphene material.