Abstract: Ammonia, as a carbon-free fuel with energy storage, has great application prospects in the energy field. However, the ammonia combustion characteristics are significantly different from conventional hydrocarbon fuels. In this paper, the moderate or intense low-oxygen dilution (MILD) combustion characteristics of CH₄/NH₃ mixture are studied by using the numerical simulation method. The results show that adding NH₃ to methane MILD combustion sharply increases outlet NO emissions. When the excess air coefficient is greater than 1, reducing it will lead to a reduction in the emission of NO and CO. The conversion rate of N in NH₃ to NO decreases with the increase of ammonia in mixture and the decrease of the excess air ratio.