Based on a set of mathematical models describing the physical and chemical processes（gas-solid flow，pulverized coal combustion，zone heat flux of clinker，and NO formation and reduction）in a cement rotary kiln，the distributions of gas temperature and gas components（O2，CO，NO）were obtained by numerical simulation of a 3000 t·d-1 full scale cement rotary kiln with four-channel burner.Besides，the mechanisms of NO formation and reduction in the cement rotary kiln were analyzed.The results indicated that the amount of NO mainly came from thermal NO and fuel NO.Thermal NO played a dominant role in the NO amount.Fuel NO was mainly formed in the combustion zone，while thermal NO was mainly formed in the high temperature sintering zone.In addition，mutual inhibition existed in the formation process of fuel NO and thermal NO.