Under the background of global carbon emission reduction,the carbon-free fuel industry faces both great opportunities and challenges. Ammonia,as an alternative of fossil energy,has the advantages of mature industrial production technology,easy storage and transportation,and zero carbon emission,et al. The research and application of ammonia fuel is one of the promising pathway to improve China′s traditional energy structure and achieve carbon emission reduction target. However,there are still some remaining problems in ammonia combustion,such as unstable combustion,low laminar flame velocity and high NOx emission. Therefore,the research on ammonia combustion technology is urgently needed. Combined with the recent achievements of ammonia combustion technology at home and abroad,the burning characteristic of the ammonia as a fuel and chemical reaction kinetics were reviewed. Specifically,the research progress of ammonia fuel in different applications including gas turbines,internal combustion engine,fuel cell and boiler were introduced. Compared with traditional fuels such as hydrogen and methane,the ammonia laminar flame velocity is low and the reaction activity is weak,which brings challenges to the optimization design of burner. For different mixing systems,the rich kinetic models of ammonia chemical reactions were established,laying the foundation for ammonia combustion applications. Pure ammonia combustion tests have been completed for ammonia-fueled gas turbines and combined with SCR devices,the lower NOx emissions can be achieved,The combustion performance of ammonia in the combustor is further optimized by technologies such as mild combustion and liquid ammonia injection. The research results show that ammonia can be blended in internal combustion engines by mixing in a large proportion,and when the blending ratio is less than 60%,the lower emissions can be achieved. The feasibility of mixed combustion of 20% ammonia can be proved by the experiment of small proportion mixed combustion of ammonia and coal. The effect of different injection locations on emissions was explored. The problems of current ammonia combustion technology research were pointed out and the future development focus direction was prospected. It is pointed out that ammonia/hydrogen fuel system is the focus of future research,and in the field of gas turbine and internal combustion engine,technologies such as burner design,injection strategy optimization will greatly improve the combustion performance of ammonia,and ammonia/coal blending boiler experiments are urgently needed.