Entrained-flow gasification is an important way for clean and efficient utilization of coal,while Zhundong coal with high contentof calcium and magnesium can not be directly applied to industrial gasifiers due to its high ash fusion temperature. The in-depth study ofthe high-temperature fusion mechanism of Zhundong coal ash has important guiding signification for its gasification application. The fusi⁃bility and mineral transformation of high calcium magnesium Zhundong coal ash under high-temperature(1 100- 1 500 ℃ ) gasifica⁃tion conditions were studied using experimental analysis and calculated simulations, and the effect of SiO2 addition on the fusibilityand mineral transformation of raw coal ash was also investigated. The results indicate that when the gasification temperature is below1 300 ℃ , Ca mainly exists in the form of CaS in the high calcium-magnesium Wucaiwan coal ash, while Mg always exists in the formof MgO. When the gasification temperature increases to 1 400 ℃ , Ca-based minerals gradually melt in the liquid phase and complete⁃ly melt at 1 500 ℃ , while Mg reacts to form magnesium aluminum spinel of high melting point, resulting in a higher fusion temperature ofraw coal ash. An appropriate amount of SiO2 can combine with Ca and Mg in coal ash to form the akermanite that is prone to low-tempera⁃ture eutectic, thus significantly reducing the fusion and liquidus temperature of coal ash. Moreover, the combined priority of SiO2 and CaOis higher than that of MgO. The thermodynamic simulation results show that some Ca and Mg in Wucaiwan coal ash still exist in the formof monoxideat the equilibrium state of 1 600 ℃ , leading to a higher liquidus temperature of the raw coal ash. The thermodynamic calcula⁃tion results can provide a reference for fusibility prediction and high-temperature mineral transformation of coal ash.