In this paper, two high-sulfur coals were selected from Yazhou and Donglin mines of China. Inorganic sulfur was completely removed first, then the tested samples were experimented under various conditions: hydrolysis, oxidation, reduction, and supercritical extraction with methanol. The change in organic sulfur was investigated. It was found that approximately 40-60% organic sulfur in coal was released at the temperature of 350°C. The removed organic sulfur was thioalcohol and thioether, while the remaining part in coal was thiophenic sulfur.