Abstract: Synthetic char was used as the mineral carrier to study the characteristic of fine particulates formation during coal combustion. The silica oxide and aluminum oxide were added to synthetic char to study the interaction between sodium and common minerals in coal. The results show that the inorganic water-soluble sodium is more likely to form stable fine particles, while organic sodium is preferred to react with silica and aluminum compounds in the absence of chlorine. Chemical reactions and physical capture are two main ways for sodium capture by silica, aluminum compounds. The sodium captured through chemical reactions is 2.4 times that by physical way.