Abstract: To investigate the coupling effects of sludge co-firing on the performance and pollutant formation of coal-fired boilers, the 2×660 MW supercritical units at Guoneng Nanning Power Generation Co., Ltd. were taken as the research object, and an integrated system model of sludge co-firing power generation and pollutant control was established based on Aspen Plus. The reliability of the model was verified by comparing the simulation results with the actual boiler operating parameters, with all errors within an acceptable range. The effects of sludge co-firing ratios (0~8%) and excess air ratios (1.05~1.50) on the boiler thermal performance and the formation characteristics of NO and SO₂ were systematically studied, and the intrinsic coupling relationship between boiler thermal efficiency and pollutant formation was analyzed. The results showed that, when the sludge co-firing ratio increased from 0 to 8%, the flue gas flow rate increased by 26490 m³/h, the furnace combustion temperature decreased by 30 ℃, the exhaust gas temperature rose by 5.6 ℃, and the boiler thermal efficiency decreased by 0.28%; meanwhile, the concentrations of NO and SO₂ in the flue gas decreased by 136 mg/m³ and 99 mg/m³, respectively (dry basis, O₂=6%), the two exhibiting a significant negative correlation. As the excess air ratio increased, both the boiler thermal efficiency and the NO formation exhibited a trend of first increasing and then decreasing, with the thermal efficiency reaching a peak of 91.74% at an excess air ratio of 1.25, while the SO₂ concentration decreased continuously. This study also identified an excess air ratio of 1.25 as the synergistically optimal value for boiler performance and pollutant emission under low-proportion sludge co-firing; at a low sludge co-firing ratio, co-firing has a slight impact on boiler performance while also achieving pollutant reduction. The model established in this study reveals the generation and variation characteristics of boiler thermal efficiency and pollutants under different sludge co-firing conditions, providing a quantitative scientific basis and engineering reference for the optimization and upgrading of sludge co-disposal technology in coal-fired power plants.