Abstract: The fly ashes melting was teased in a selfdeveloped swirling melting furnace system. The influences of calcium oxide, silicon dioxide, magnesia additives on the melting characteristics were studied during fly ashes melting process. When the amount of calcium oxide added is 5 percent, there is a effective control action on the melting point of fly ash. The amounts of crystals are lessened in the slag, and the stability of slag is enhanced. The meltingaid effect of calcium oxide can be appropriately adjusted based on the composition of fly ash. Adding silicon dioxide in the fly ash can redound to reducing the melting point of fly ash and promote the liquidity of sample. With the increasing of silicon dioxide added, the glassy amorphous materials in the melted sample are increased. The higher the adding amount of silicon dioxide, the better is the stability of melted slag. The netlike structures of silicates in the fly ash will be destroyed by adding the magnesia. The glutinosity of melted sample reduces with increasing the adding amount of magnesia. The glassy materials in the slag can be increased and the crystal phases transform can take place with adulterating magnesia. The crystals in the sample are enveloped by the amorphous slag. The sample would achieve the better melting effect when the adding amount is more than 5 percent in fly ash sample.