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[Display omitted] • Multi-stage circulation integrated SO 2 and CO 2 capture, coupled with NH 3 recovery. • Over 99.5% SO 2 and 70% CO 2 was captured with desorption duty of 2.48 GJ/t CO 2. • Adaptable strategies balanced efficiency and economy amid complex conditions. Amidst growing environmental concerns stemming from fossil fuel combustion, which releases a considerable amount of pollutants and greenhouse gas. In an effort to mitigate the costs of existing combustion flue gas desulfurization and CO 2 capture systems, a new multi-stage circulation (MSC) process for integrating capture of CO 2 and SO 2 using ammonia-based absorbents was proposed. Different functional zones were interconnected using ammonia (NH 3) and potassium carbonate (K 2 CO 3) blended solution as the absorbent, enabling efficient SO 2 capture in the 1st stage, CO 2 enrichment in the 2nd stage, CO 2 capture enhancement in the 3rd stage and recovery of escaped NH 3 in the 4th stage. Experimental results demonstrated the effectiveness of NH 3 /K 2 CO 3 solution in enhancing CO 2 capture efficiency. The overall CO 2 capture efficiency varied between 95.4 % and 84.1 % at inlet CO 2 concentrations ranging from 5 % to 30 %. Under typical combustion flue gas conditions of 622 ppm SO 2 and 15 vol% CO 2 , the process exhibited a SO 2 removal efficiency exceeding 99.5 %, with CO 2 capture efficiency surpassing 70 %. Furthermore, the CO 2 desorption duty was determined to be 2.48 GJ/t CO 2. 13C NMR results confirmed that simultaneous absorption of CO 2 and SO 2 led to the accumulation of SO 2 in the liquid phase, reducing the CO 2 loading in rich solvent. To address these challenges, coupled optimization strategies was proposed, ensuring high capture efficiency and low CO 2 desorption duty under the complex and variable conditions of flue gas parameters, SO 2 concentration, and CO 2 concentration. [ABSTRACT FROM AUTHOR]