The primary aim of this study is to understand the effect of SiO2 on the fusibility and flow behavior of high-calcium coal ash and to investigate the mineral materials transformation at high temperatures. The changes of ash fusion temperature and viscosity at different coal-SiO2 blended ratio were researched. The results show that the ash fusion temperature of Shanxin blending coal reaches the minimum when SiO2/Al2O3 (S/A) weight ratio is 7.36 and acid to basic ratio (A/B) is 1.23. The mineral matters variation of Shanxin coal ash was compared with that of S/A = 7.36 Shanxin blending coal ash by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicate that the fluidity of slag has been improved by the Si content in minerals. FactSage was used to predict the optimum value of flux and to demonstrate the mineral matters variation and these results agree well with the experimental values.