The invention provides a preparation method for a nitrogen-doped carbon oxygen reduction catalyst with a hierarchical porous structure, belonging to the technical field of a fuel cell. The preparation method comprises the following steps of: firstly, preparing a eutectic molten salt having a three-dimensional macro-porous structure by a freeze drying method; secondly, using the eutectic molten salt as a template, doping a nitrogen-containing precursor, and leading the nitrogen-containing precursor to be oxidized and polymerized on the surface of the eutectic molten salt by a solid-phase polymerization method, wherein ammonium persulfate serves as an oxidizing agent, and a ferric salt serves as a promoter; and finally, carrying out high-temperature pyrolysis and removing the eutectic molten salt. With the adoption of the nitrogen-doped carbon oxygen reduction catalyst with the hierarchical porous structure, the nitrogen-containing precursor can be effectively prevented from pyrolysis loss, structural collapse and sintering during the high-temperature carbonation process, the catalyst yield and the nitrogen doping efficiency are improved, moreover, a large amount of micropores, mesoporous and macropores can be generated, and the mass transfer efficiency of oxygen and water is improved. The method is simple and practical, the production cost is low, and the prepared catalyst has excellent oxygen reduction catalytic activity and can substitute the traditional commercial Pt/C catalyst.