Abstract: In the context of carbon neutrality, selecting low-carbon fuel ammonia for the retrofitting of coal-fired power plants is particularly important. This paper first introduces the basic physical properties of ammonia and the advantages of ammonia co-firing. It then focuses on new applications of ammonia-coal co-firing technology, classifying it according to the output power of coal-fired equipment. This includes small-scale ammonia co-firing burners, kilowatt-level coal-fired ammonia co-firing systems, megawatt-level systems, and large-scale coal-fired power plant ammonia co-firing systems, detailing the current research progress. Finally, the paper analyzes and forecasts the prospects of ammonia co-firing in coal-fired power plants. Ammonia co-firing in coal-fired power plants can significantly reduce carbon emissions, although it may lead to NO_x emission issues. NO_x emissions can be effectively controlled through staged air supply, ammonia pre-decomposition, and adjusting the ammonia injection position and ratio. Finally, challenges remain in addressing the significant differences in the reactivity of coal and ammonia gas-solid fuels, high NO_x concentrations, lack of large-capacity high-ratio co-firing burner technology, and achieving breakthrough in key technologies related to "large-scale ammonia supply, clean ammonia combustion, and flexible operation."