Methods of experimental research and quantum chemical calculation were combined to study the effect of kaolin on ash melting characteristics of Zhundong high alkali coal and the mineral evolution law during ash melting processes. Furthermore, the behavior mechanism of kaolin capturing alkali metal was also studied from the perspective of mineral microstructure features. The results show that the melting temperature of Zhundong high alkali coal ash have rapid rise first and then gradually decreased with the amounts of kaolin increasing. When the adding proportion of kaolin is greater than 10%, the improving efficiency on the ash melting temperature become weakened. Once kaolin was added in Zhundong high alkali coal, anorthite, anhydrite, albite, and muscovite would be generated among the temperature range from 1000 to 1200 degrees C, Na+ or K+ that easy to volatile and form eutectics have been captured by the Si-Al system, some mullite generated among the temperature range from 1200 to 1300 degrees C. Investigating the capture mechanism, it indicates that O (26) and O (22) have electrophilic reaction with Na+ and K+ easily, which would promote the rupture of aluminum oxygen bonds. The O2- of alkali metal or alkaline earth metal oxide would easily have nucleophilic reaction with Si (6) and Si (8) and prompt the rupture of bridging oxygen bonds (Si-O-Si). Kaolinite would be transformed into high melting point minerals that contain Na+ or K+ which have trend to form eutectics or evaporate into the flue gas easily, and the degree of fouling and slagging on the heating surface can be reduced based on the two easiest reaction paths.