Abstract: To address the contradiction of achieving low nitrogen emissions while maintaining high-efficiency combustion in coal-fired boilers, a 300 MW coal-fired boiler at a power plant, and systematically studies the formation characteristics of NO_x during boiler combustion and its relationship with CO and O₂ concentration are systematically studied. The correlation models for NO–CO, boiler efficiency–CO, NO–O₂ and CO–O₂ under different loads were established, and the CO/O₂ dual-parameter comprehensive combustion optimization model was constructed. By analyzing the historical operation data of the boiler, it is found that there is a significant correlation between boiler efficiency and NOx emission and CO generation. The results show that by adjusting the air volume, the combustion state of the boiler can be optimized, the boiler efficiency can be improved and the NO_x emission concentration can be effectively controlled. The optimization and adjustment under typical loads such as 300, 250 and 150 MW verified the effectiveness of the model and realized the high efficiency and deep low nitrogen combustion in the boiler. The proposed CO/O₂ dual-parameter control combustion optimization strategy is of great significance for guiding coal-fired power plants to achieve the dual goals of environmental protection and economic benefits.