Abstract: The effect of vermiculite on the slagging characteristics of high-sodium and high-calcium Zhundong coal was studied by a drop-tube furnace and with ash fusion tester. The results show that with the increase of the amount of vermiculite blended, the ash melting point temperature first decreases and then increases. When the ratio of blending is 6%, the ash fusion point temperature is the lowest. The higher the blending ratio is, the more obvious the improvement of the slagging condition of Zhundong coal is. When the ratio of blending is 4%, the slag sample becomes loose and porous, the texture turns to be brittle, and the adhesion between the slag sample and the deposition probe is weak, being easy to be removed by soot blowing. It is recommended that the amount of vermiculite blended should be 4%. The original mineral in coal ash is mainly composed of quartz, gehlenite and low fusion point minerals of pyroxene. After blending vermiculite, the omphacite, sodium-containing minerals, is converted into pargasite, and the iron-bearing minerals such as augite and hematite are converted into forsterite ferroan, and the minerals in the slag sample are mainly forsterite, which has a high fusion point. Sodium can be captured by vermiculite. With the sampling temperature decreasing and the vermiculite blending ratio increasing, the effect of sodium capture becomes more and more obvious.