Abstract: Carbothermal reduction of NO_x in flue gas is an effective method to reduce NO_x emissions from coal-fired cement kilns. Focusing on the practical application of this method in the field of cement kilns, the 2500t/d cement kiln production line of a cement company in Ningxia is taken as the research object, and the computational fluid dynamics (CFD) method is used to conduct numerical simulation research on carbothermal reduction of NO_x in flue gas. The influences of initial O₂ contents in flue gas at C5 outlet, initial temperatures in flue gas at C5 outlet and coal feeding rates on carbothermal reduction effect of flue gas are explored. The simulation results show that with the decrease of the initial O₂ content in flue gas, the reduction efficiency of NO_x gradually increases, but the heat exchange efficiency becomes worse. When the initial flue gas temperature is in the range of 1023.15~1123.15K, the NO_x reduction efficiency decreases first and then increases with the increase of the initial flue gas temperature. With the increase of coal feeding rate, the NO_x reduction efficiency gradually increases. Overall, the initial O₂ content of flue gas should be controlled at about 1%, and the initial temperature of flue gas at 1048.15K is suitable. Considering the temperature rise of flue gas and raw material and NO_x reduction effect, the coal feeding rate should be controlled at 700kg/h. The results of this study can provide important theoretical guidance and reference for the practical application of flue gas carbothermal reduction technology in cement kilns.