The invention provides a system and method for reducing NOx generated by combustion of a W flame boiler. The system is simple in structure, rational in design, and safe and controllable in operation,and the concentration of the NOx generated by combustion of a low volatile coal fired boiler can be reduced effectively. The system comprises a furnace, a burner arranged on the furnace, flue gas nozzles arranged at the arch part of the boiler and the lower furnace position separately, and a flue gas recirculation system; the flue gas recirculation system comprises a high temperature flue gas mixing inlet pipeline, a flue gas fan and a high temperature flue gas outlet main pipeline which are connected in sequence according to the flue gas flow direction; the input end of the high temperature flue gas mixing inlet pipeline is separately connected with different positions of a tail flue of the furnace for pumping out high temperature flue gas; and the output end of the high temperature fluegas outlet main pipeline is connected with the burner and the flue gas nozzles, and used for introducing high temperature flue gas into the furnace circularly. Through strengthening of preliminary burning of low volatile coal, the oxygen quantity of the preliminary stage of pulverized coal combustion is reduced, and the formation of a local high temperature area of the furnace is inhibited; and the purpose of controlling and reducing the NOx generated by combustion is achieved.