Abstract: In response to the issues of decreased denitration efficiency of the SNCR (Selective Non-atalytic Reduction, SNCR) system, difficulties in achieving ultra-low NO_x emissions, and increased ammonia slip caused by the enhanced operational flexibility of CFB (Circulating Fluidized Bed), boilers, a novel technical solution was developed using a 300 MW CFB boiler as the research subject. Firstly, an online gas component partition monitoring system was designed and installed, enabling precise measurement of gas components in various regions of the furnace, which guided differentiated control strategies. Secondly, the SNCR denitration system was retrofitted to allow for the regulation of urea quantity with the separator as the control unit. By combining the total urea flow with the component control unit of the separator, a "real-time measurement, partitioned control, collaborative optimization, and overall optimization" approach was achieved. Finally, the control strategy was optimized based on the monitoring results, enhancing the uniformity and stability of NO_x emissions. This improved denitration efficiency while reducing the urea consumption per unit of power generation. These efforts resulted in precise monitoring of the boiler combustion process and effective control of pollutant emissions, meeting ultra-low emission standards. The urea savings ranged from 12.05% to 18.1%, and the fluctuation of NO_x emissions was reduced from 8%–12% to below 5%. This research provides a valuable reference for NO_x emission control and the optimization of SNCR denitration systems in CFB boilers, significantly contributing to the enhancement of environmental friendliness and operational flexibility of CFB boilers.