Abstract: Experimental study on the slagging characteristics of Yulin & Pingshuo blended coals was carried out in a drop tube furnace. The slagging indexes were determined at different temperatures and the quantitative analysis on the composition of mineral matters in the ash slag was made using X-ray diffraction analysis (XRD). The results indicated that four crystalline minerals-iron oxide, anorthite, mullite, silica, and another amorphous glass are mainly consisted of the ash slag and the first three have a significant effect on the slagging tendency of coals. Higher content of iron oxide in the ash and anorthite in the ash slag, together with lower content of mullite in the ash slag leads to greater slagging tendency. According to this, using coal blending to obtain lower iron oxide content, and to decrease and increase the formation quantity of anorthite and mullite respectively, the slagging tendency of Shenmu type coal could be inhibited at a lower level.