In this work, high-value-added N-doped hierarchical porous carbon (NHPC) for oxygen reduction reaction (ORR) electrocatalysis was prepared using biomass cellulose as the raw material. The pyrolysis of cellulose is accelerated by a redox combustion reaction of magnesium nitrate carbohydrates (urea and cellulose) as absorbed in cellulose fibers, which endows doping with nitrogen, exfoliates the cellulose to highly porous particles, and creates numerous pores simultaneously. After being further carbonized at high temperature and washed with acid, NHPCs were produced that have hierarchical porous structure and large specific surface area. These features are beneficial to the ORR. The influence of four preparation parameters, including species of magnesium salt, carbonization temperature, urea amount, and magnesium salt amount, on the porous characteristics and ORR performance is comprehensively investigated.