Abstract: High alkali metal coal from four coal mines in Zhundong coalfield and its gasification fly ash were used to investigate the occurrence of alkali metal with five pretreatment methods including low temperature ashing,microwave digestion,national standards,cascade extraction and oxygen bomb combustion.The results show that the sodium in the high alkali metal coal exists mainly in the water soluble form,and the potassium is in the water insoluble form;The method of oxygen bomb combustion is the optimum one to determine the content of Na and K in high alkali coal and gasification fly ash,and the method of cascade extraction is also a better one to determine the content of Na.