Abstract: Aiming at the problem of energy abandonment of wind-photovoltaic-thermal integrated energy system with high wind and photovoltaic penetration rate, this paper proposes using the technology of power-to-ammonia and ammonia mixed combustion of thermal power units to improve the utilization rate of wind and photovoltaic energy and improve the safety and environmental protection of coal based energy systems in China. First, the power-to-ammonia coupling integrated energy system is proposed, and the coordinated operation index of wind-photovoltaic-thermal-ammonia system is defined for the comprehensive evaluation of the economy and stability of coal-fired unit output, wind and photovoltaic energy consumption and power-to-ammonia operation. Then, a bi-level optimal scheduling model is established, with the maximum coordinated operation index of the system as the upper goal, and the minimum operation cost of the power-to-ammonia coupling integrated energy system as the lower goal. Finally, the validity of the proposed model is verified by comparing different cases in multiple scenarios. The results show that under the typical day scenarios in winter, transition season and summer, for the integrated energy system without power-to-ammonia, the total cost of the system is reduced, while the stability and safety of coal-fired units are improved. After the introduction of power-to-ammonia, the absorption rate of wind-photovoltaic power is improved, and the total cost is further reduced by 1.06%, 1.74% and 0.59%, respectively. The carbon emissions are decreased by 2.11%, 2.81% and 1.95%, respectively. It can be seen that power-to- ammonia has a good improvement effect on the economic and low-carbon operation of the integrated energy system.