Abstract: Xinwen CWS (Coal-Water-Slurry) and black liquor CWS were combusted in a 0.25?MW combustion furnace, and the slag produced along the furnace was measured and analyzed to determine the distribution of mineral species such as Na, K, Ca, Al, Si and Fe. The influence of mineral species on the fusion is discussed. The result shows that the distribution is different among the mineral species along the fire in the furnace. For example, Na2O on the wall is less than that in the volume, and the distribution increases firstly, then decreases after it reaches the peak at 1 000 mm. And the distribution of some other mineral species has their own rule which is consistent with the fusibility of the coal ash.