Abstract: Natural gas power plants will play an important role in scenarios with high renewable energy input due to their clean, efficient and excellent peak-shaving capacity. Although natural gas power plants have lower carbon emission intensity compared to coal-fired power plants, they remain a major source of global CO₂ emissions. CO₂ capture, utilization, and storage （CCUS） technologies are essential for achieving carbon neutrality, with post-combustion calcium looping technology drawing significant attention due to the widespread availability and low cost of its absorbents. Traditional oxy-fuel calcium looping capture technology uses pure oxygen and fossil fuels to supply heat for the calcination process and recovers the constant-temperature heat from the carbonation reaction by directly heating steam, resulting in high energy penalties. A novel ammonia-driven calcium looping CO₂ capture system for natural gas-ammonia complementary power generation has been proposed, in which ammonia replaces fossil fuels as a zero-carbon fuel. This new system avoids the additional carbon capture demand caused by fossil energy heating and utilizes ammonia pyrolysis to recover medium-temperature heat released from the carbonation reaction, avoiding large temperature difference heat exchange losses when directly heating steam. The results show that, compared to traditional oxy-fuel calcium looping systems, the efficiency penalty of the new system drops from 9.4% to 0.6%, and the CO₂ avoided energy consumption decreases from 4.7 to −8.1 MJ/kg, significantly improving its thermodynamic performance. At the same time, the carbon emission intensity of the new system is significantly reduced compared to the oxy-fuel calcium looping system, reaching 18.6 kg/MWh. An analysis of the effect of gas turbine inlet temperature and pressure at ammonia side on the new system’s performance shows that the new system performs well across a wide range of operating parameters.