The accumulation of nitrogen in aquaculture wastewater may cause eutrophication. In order to remove nitrogen from wastewater, a traditional biological denitrification process of autotrophic nitrification and heterotrophic denitrification is usually used, and the emergence of heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria is a breakthrough in biological nitrogen removal. HN-AD bacteria can perform simultaneous nitrification and denitrification, with the benefits of wide distribution, high adaptability, short generation time, and rapid biodegradability. As a result, it has a wide range of applications in the field of aquaculture wastewater treatment. The biological characteristics, influencing factors, mechanisms, related catalytic enzymes, and application of HN-AD bacteria in practical wastewater treatment were systematically reviewed in this paper. Suggestions for HN-AD strain screening, nitrogen removal principle, and practical application were provided.[Chinese Fishery Quality and Standards, 2023, 13 (1): 33-41]