The invention provides a preparation method of a nitrogen-doped porous carbon material based on citric acid transition / alkali metal complex salt. The preparation method comprises the following steps:taking the citric acid transition / alkali metal complex salt as a carbon source, in the atmosphere containing ammonia gas, performing heat treatment for 1-24h under the temperature of 500-1,000 DEG C;after cooling, performing acid washing to remove impurities such as metal, and then washing with water to remove excess acid solution to neutral, and obtaining the nitrogen-doped porous carbon material after drying. The preparation method provided by the invention is simple and no pore-forming agent is needed, the preparation method is easy to operate, raw materials are wide in source, the methodis green and environmentally friendly, low in cost, is beneficial to realize larger-scale industrialized production, the prepared nitrogen-doped porous carbon material has the advantages that the nitrogen-doped porous carbon material has a multi-stage hole structure, a lamellar structure containing holes and has obvious graphite lattice fringes, the specific surface area is large, and the nitrogen-doped porous carbon material is rich in nitrogen heteroatoms and oxygen reduction activity point locations, has the good electrical catalysis oxygen reduction performance and stable performance, canbe used for preparing electricity catalysis oxygen reduction electrode and other catalyst carriers.