Abstract: Chemical looping combustion （CLC） is an innovative low-carbon combustion technology with inherent CO₂ separation capabilities. However, the design and operational optimization of large-scale CLC reactors remain challenging. To address this issue, this study developed a one-dimensional order-reduced model to simulate the performance of a 10 MW coal-fuelled dual circulating fluidized bed （CFB） CLC system, with a focus on the coupling between the fuel reactor （FR） and the air reactor （AR）. The model characterized the gas-solid flow patterns, reaction progression, and temperature distributions within the two main reactors. Furthermore, it elucidated the steady-state operational behavior under interconnected reactor conditions: in the FR, the gas–solid mass transfer rate in the dense region was identified as the rate-limiting step for fuel conversion, while the sharp decay of oxygen carrier （OC） fraction in the dilute region resulted in the escape of unburned gases; in the AR, a gas reverse overflow phenomenon significantly enhanced the oxidation reaction in the dense region. Under baseline conditions, the system achieved a solid circulation rate of 95 kg/s and a combustion efficiency of 95.3%; however, limited by char conversion, the carbon capture efficiency reached only 67.6%. Subsequently, a detailed analysis was performed to evaluate the effects of key operating parameters, including FR temperature, FR solid inventory, char separator efficiency, and oxygen-to-fuel ratio. The results indicated that increasing the FR temperature and char separator efficiency effectively improved system performance. Although raising the FR solid inventory had a beneficial effect, its enhancement gradually diminished as the height of the dilute region decreased. Increasing the oxygen-to-fuel ratio was found to adversely affect carbon capture. Sensitivity analysis confirmed that the FR temperature is the most critical factor affecting combustion efficiency, while the char separator efficiency predominantly governs the carbon capture efficiency. Based on these findings, the primary optimization strategies for such reactors are proposed as follows: increasing the char separator efficiency beyond 95% while maximizing the FR operating temperature within the limits of material tolerance.