Abstract: Against the background of simultaneous deep emission reduction and flexible peak regulation in coal-fired power plants, the operation of flue gas desulfurization and denitration systems has shifted from simple compliance with environmental standards to refined regulation featuring high efficiency, low consumption and collaboration. Taking a typical 2×660MW ultra-supercritical coal-fired unit as the research object, focusing on the two core processes of limestone-gypsum wet flue gas desulfurization and selective catalytic reduction (SCR) denitration, this paper systematically sorts out the influence rules of key parameters such as absorption tower slurry quality, liquid-gas ratio, oxidation air volume, SCR reactor temperature window and ammonia injection uniformity on system performance. Operation practice shows that controlling the pH value of the absorption tower slurry in the range of 5.6-5.8 by load interval, maintaining the slurry density at 1080-1140kg/m3, and dynamically adjusting the liquid-gas ratio within 8.5-12.5L/m3 can significantly reduce the plant power consumption rate while ensuring desulfurization efficiency. On the denitration side, by optimizing the distribution of ammonia injection grid and ammonia-nitrogen molar ratio, the ammonia slip concentration is controlled below 3μL/L, which effectively delays the blockage of air preheater. The research results can provide technical reference for ultra-low emission and economic operation of similar units.