Abstract: Traditional compressed air energy storage (CAES) systems are constrained by the inherent thermodynamic char-acteristics of the compression–expansion cycle, leading to generally low round-trip efficiency and insufficient energy storage density. Although solid oxide fuel cells (SOFC) offer high energy conversion efficiency, their pressurized operation requires significant compressor work, and they lack intrinsic energy storage and load-following capabilities, making them difficult to adapt to the variability associated with high penetration of re-newable energy integration. Current research on SOFC system integration has mainly focused on waste heat cas-cade utilization, while studies on its deep coupling with compressed air energy storage systems to achieve a mul-ti-energy synergistic mechanism of “energy storage–power generation–combined heat and power” remain lim-ited. Therefore, based on the principle of energy cascade utilization, this study proposes an integrated combined heat and power system coupling compressed air energy storage with a solid oxide fuel cell–gas turbine–steam turbine (SOFC–GT–ST) combined cycle. During the charging stage, surplus off-peak electricity is used to drive air compression for storage. During the discharging stage, the stored high-pressure air replaces the original SOFC air compression process, thereby reducing system auxiliary power consumption. A full-condition thermo-dynamic model of the system is developed using Aspen Plus, and exergy analysis as well as energy utilization diagram (EUD) analysis are conducted to reveal the influence mechanisms of key parameters on system perfor-mance. The results show that under design conditions, the system achieves a thermal efficiency, power-to-power efficiency, and exergy efficiency of 86.63%, 64.71%, and 63.11%, respectively, with an energy storage density of 7.30 kWh·m?3. Sensitivity analysis indicates that irreversibilities in fuel chemical energy conversion are signifi-cantly higher than those in thermal energy utilization processes. Among all components, the SOFC is identified as the largest source of exergy destruction due to the irreversibility of electrochemical reactions, accounting for 24.48% of the total exergy destruction, followed by the afterburner at 15.40%. The air preheater also exhibits notable exergy destruction (13.29%) due to poor thermodynamic matching between hot and cold streams. In terms of optimization, increasing SOFC operating temperature and discharge pressure can enhance power gener-ation performance and exergy efficiency, whereas increasing fuel flow rate and compressor pressure ratio leads to decreases in both power-to-power efficiency and exergy efficiency. Replacing throttling valves with expanders to recover pressure exergy, as well as improving heat exchanger network matching to reduce thermal irreversibility, are effective strategies for system optimization. This work provides a theoretical basis for the design and optimi-zation of high-efficiency long-duration energy storage systems.