Abstract: Cofiring ammonia with coal is an effective approach to realize large-scale carbon reduction for coal power plants, but due to the significant difference in combustion and pollutant formation characteristics between ammonia and coal, how to achieve high-efficiency and clean cofiring ammonia with coal is a major challenge globally. In addition, China's coal and ammonia cofiring test and demonstration started relatively late compared with foreign countries, and the research results and core technology of each research institution are in the stage of blocking, it is still in absence of systematic operation guidance for ammonia cofiring in large coal power plants. To this end, based on a 1000 MW opposed wall coal-firing boiler, simulations have been carried out with 20% and 40% ammonia blending ratios (heat basis) using Fluent commercial software, in order to figure out the optimal ammonia mixing pattern, location and combination configuration. Firstly, the influence of mixing pattern between ammonia and primary air on combustion and pollutant emission is studied under 20% cofiring ratio, and it reveals that the ignition stability of ammonia can be enhanced by making primary air as overfired air and using non-premixed cofiring pattern, moreover, the fuel-NO conversion can be inhibited and the NO emission can be reduced. Subsequently, the ammonia cofiring location is optimized under 20% cofiring ratio (shut down one mill), the result demonstrates that cofiring ammonia in the middle layer (B, E) would facilitate C-N interaction, and lead to substantial NO formation, but cofiring ammonia in upper (C) or lower (A, D) layer can avoid high NO in the burner exit, and consequently to lower the NO emission. Next, the ammonia cofiring location combination is studied under 40% cofiring ratio (shut down two mills). The results indicate likewise that cofiring ammonia via the middle layer (B, E) should be avoided, while the best combination is A-C configuration. Lastly, the exhausted gas parameters are compared for different cofiring ratios, the results indicate that the flue gas volumetric flowrate and temperature will be promoted with the ammonia cofiring ratio, so the compatibility modification of the heating surfaces would become a new question that needs to be solved for ammonia cofiring with coal in boilers in the future.