Abstract: Based on the study of coal combustion,the main reason of low calorific efficiency was analyzed.Experiment and theoretical value proved that the additive can lower ignition temperature,hasten the coal combustion and calorific efficiency.The reaction mechanism of the additive of the coal combustion was put forward.The big molecule of coal break down by the additive affixture,it can accelerate releasing of coal volatiles,make the coal lower ignition temperature.It was possible to use different additive together,this way can recruit oxygen gas during the coal burning and make the coal combustion burn well.Mechanism study on chemical additive during coal combustion is significant for study of the additive.