NOx as a major gaseous contaminant, reducing NOx emissions has become a pressing concerns. At present, the SNCR process is preferred for waste-to-energy power plants. In this paper, a method of low-nitrogen combustion system with flue gas circulation combined with SNCR was proposed to reduce NOx emissions. A portion of the hot flue gas at the tail of the furnace is extracted as circulation flue gas, and the circulation flue gas is sprayed into the SNCR as tertiary air. The experimental research was conducted in a 500 t/d waste-to-energy power plant. Firstly, the air distribution of the incinerator with the low-nitrogen combustion system is discussed, the circulation flue gas can completely replace the secondary air to reach the boiler rated evaporating capacity and reduce NOx emissions. Next, the supply position of the tertiary air was studied, and the supply position worked best in the upper of SNCR. Finally, the usage of the low-nitrogen combustion system can reduce urea consumption by around 35%. The circulation flue gas extracted in the incinerator contains a small amount of particulate matter. It is a problem to be considered for further industrial application.