In view of the problems of the grate-rotary kiln pelleting process, such as high NOx emission concentration in exhaust gas, high cost in investment and operation of terminal treatment, and based on the systematic analysis of the NO_x emission laws and its influencing factors, a series of studies on the collaborative treatment technology of source control, process control and selective catalytic reduction (SCR) for the NO_x emission reduction are carried out. The results show that low NO_x combustion technology, low NO_x burner technology and low temperature roasting technology are the most effective methods to reduce the NO_x generation in pellet production. The advanced reburning technology is the most direct technical means to reduce the end treatment load, and the removal efficiency of NO_x in exhaust gas can exceed 60%, thus ensuring that the NO_x concentration of the exhaust gas in the second preheating zone below 300 mg/m³. By effectively restraining the movement of gas from the second preheating zone to the first preheating zone, and by taking advantage of the medium and high temperature conditions of the flue gas, the SCR denitrification system is added after the multicyclone deduster, there is no need for raising temperature and the volume of exhaust gas which needs to be treated can be reduced by over 50%. The oxygen content of flue gas reaches 15%~18% in this stage, and the ultra-low emission target can be obtained when the denitrification efficiency of SCR reaches 90%. Compared with the traditional technique of terminal treatment of NO_x, the construction cost and running cost can be saved by 1/3 and 2/3 respectively.