Abstract: Under the dual carbon goals, co-firing of ammonia and coal has become an effective way to reduce carbon emissions from coal-fired power plants. The inherent mineral Fe in coal significantly affects the formation of NO during coal combustion, but its influence on the formation of NO and the migration and transformation pathways of N during homogeneous combustion of ammonia and coal volatiles and heterogeneous combustion of ammonia and coal char remains unclear. Based on this, this paper uses a high-temperature tube furnace experimental platform and CHEMKIN software to explore the effects of mineral Fe on NO formation characteristics and N transformation pathways in two different combustion systems. The results show that mineral Fe can effectively inhibit NO emissions in both the homogeneous combustion stage and the heterogeneous combustion stage, with the best effect at 1400°C. Mechanism analysis indicates that the inhibition of NO in the two different combustion systems is mainly due to the participation of R1384: FEO2 + O <=> FEO + O2 and R1403: FEO2H2 + H <=> FEOH + H2O, and Fe mainly inhibits NO formation indirectly by consuming free radicals such as H, OH, and O. The NO yield of Fe-impregnated coal varies in two different combustion systems. In the homogeneous combustion system, the formation of NO mainly occurs through reactions R690：HNO+O2<=>HO2+NO and R706：NO2+H<=>NO+OH, while in the heterogeneous combustion system, it mainly results from reactions R690 and R818：NH2+NO2<=>H2NO+NO. The reaction pathways of Fe-impregnated coal in the two combustion systems are the same, but the proportions of various products in the reaction pathways have changed. Compared with the heterogeneous combustion system, the proportion of the reaction converting NH3 to NH2 in the homogeneous combustion system has decreased by 46.3%. In both combustion systems, due to the instability of N2O at high temperatures, it will eventually be converted to N2 in extremely high proportions.