Abstract: As high alkali coal contains sodium, potassium and other alkali metals, it may cause coking, slagging, corrosion and other problems on the heat exchanger wall during the heat utilization process, which poses a serious threat to the safe and efficient operation of the power plant equipment. In this article, the contents of alkali metals occurrence in single-particle YCW and NMH coals are measured using inductively coupled plasma emission spectrometry (ICP-OES). Using a high-speed camera and a hyperspectral imaging system, images of the combustion process and spectral images of spontaneous radiation from the flames of single-particle YCW and NMH coals are obtained. The results show that most of the alkali metals Na* and K* exist in water-soluble forms in YCW and NMH coals; Alkali metal Na* exhibits a two-stage characteristic during the combustion process of single particle coal. and all types of alkali metal Na* are released during the combustion process, most of which are released in the form of water-soluble sodium. Insoluble alkali metals are difficult to release during the coal combustion process. Single-particle coals show early gas-phase ignition time and delayed burnout time after undergoing water-washing and acid-washing. The above studies are conducted with a view to providing a theoretical basis for constructing a kinetic model of alkali metal transformation of coal at different stages of combustion as well as controlling the release of alkali metals.