Nowadays, it has become a trend to prepare porous carbon as electrode materials for supercapacitors by using biomass and its derivatives by virtue of its low cost, abundant source and environmental friendliness. Carboxymethyl cellulose ammonium (CMC-NH4), a kind of cellulose derivative, is used as a carbon precursor and O/N source to prepare carbon material through cross-linking with aluminum ions, lyophilization, carbonization and activation. The as-prepared O/N-co-doped carbon samples (ONAC-500, ONAC-600 and ONAC-700) exhibit hierarchically porous structure with different size pores in carbon framework, ensuring electrolyte ions effective transport and diffusion. Meanwhile, the ONAC-600 reveals a high specific surface area of 2658 m(2) g(-1), abundantly porous structure with pore volume of 1.32 cm(3) g(-1) and effective O/N-doping, which ensure a high capacitance of 465.0 F g(-1) at 1 A g(-1) in 3 M KOH three-electrode system. It also shows better rate capability and good stability after 10000 cycled under 10 A g(-1). Besides, the assembled all-solid-state supercapacitor with ONAC-600 delivers an acceptable energy density of 7.8 Wh kg(-1) at a power density of 124.2 W kg(-1).