Under the background of "dual carbon", sewage treatment not only needs to achieve resource utilization, but also needs to reduce carbon emissions. To reduce N₂O emissions, scholars at home and abroad have conducted extensive research on N₂O emissions from urban sewage plants. Firstly, it was summarized that both nitrification and denitrification processes in wastewater treatment produce N₂O. The mechanism and mode of N₂O production during the reaction process also differ, and the amount of N₂O produced may vary depending on the process. Secondly, three typical biological denitrification processes for wastewater were reviewed: cyclic activated sludge system (CASS) process, anaerobic ammonium oxidation (ANAMMOX) process, and nitrosation anaerobic ammonium oxidation (CANON) process, as well as four factors affecting N₂O emissions from urban wastewater treatment plants: carbon source, dissolved oxygen concentration, temperature, and magnetic field strength. Finally, the shortcomings of current research were summarized and provided prospects from four aspects: temperature influencing conditions, carbon source types, CANON process mechanisms, and N₂O recovery and utilization. The CANON process is effective for removing N₂O, but it should be noted that a low pH in the reaction can cause NH₂OH and HNO₂ to react and produce N₂O, thereby weakening the removal effect.