Reducing NOx emission of iron ore sintering process in a cost effective manner is a challenge for the iron and steel industry at present. Effects of the proportion of mill scale and coke breeze on the NOx emission, strength of sinter, and sinter indexes were studied by com-bustion and sinter pot tests. Results showed that the peak value of NO concentration, total of NO emission, and fuel-N conversion rate gradu-ally decreased as the proportions of the mill scale increased because NO was reduced to N2 by Fe3O4, FeO, and Fe in the mill scale. The strength of sinter reached the highest value at 8.0wt％ mill scale due to the formation of minerals with low melting point. The fuel-N conver-sion rate slightly fluctuated and total NOx emission significantly decreased with the decreased proportions of coke breeze because CO forma-tion and content of N element in the sintered mixture decreased. However, the sinter strength also decreased due to the decrease in the amount of the melting minerals. Furthermore, results of the sinter pot tests indicated that NOx emission decreased. The sinter indexes performed well when the proportions of mill scale and coke breeze were 8.0wt％ and 3.70wt％ respectively in the sintered mixture.