Natural gas power plants will play an important role in scenarios with high renewable energy input due to their clean,efficientand excellent peak-shaving capacity. Although natural gas power plants have lower carbon emission intensity compared to coal-firedpower plants,they remain a major source of global CO2 emissions. CO2 capture,utilization,and storage (CCUS) technologies areessential for achieving carbon neutrality, with post-combustion calcium looping technology drawing significant attention due to thewidespread availability and low cost of its absorbents. Traditional oxy-fuel calcium looping capture technology uses pure oxygen and fossilfuels to supply heat for the calcination process and recovers the constant-temperature heat from the carbonation reaction by directlyheating steam,resulting in high energy penalties. A novel ammonia-driven calcium looping CO2 capture system for natural gas-ammoniacomplementary 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 heatreleased from the carbonation reaction, avoiding large temperature difference heat exchange losses when directly heating steam. Theresults show that,compared to traditional oxy-fuel calcium looping systems,the efficiency penalty of the new system drops from 9.4% to0.6%, and the CO2 avoided energy consumption decreases from 4.7 to −8.1 MJ/kg, significantly improving its thermodynamicperformance. At the same time,the carbon emission intensity of the new system is significantly reduced compared to the oxy-fuel calciumlooping system,reaching 18.6 kg/MWh. An analysis of the effect of gas turbine inlet temperature and pressure at ammonia side on the newsystem’s performance shows that the new system performs well across a wide range of operating parameters.