In this paper, two high-sulfur coals were selected from Yanzhou 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 40-50% organic sulfur in coal was released at the temperature of 350 degrees C. The removed organic sulfur was thioalcohol and thioether, while the remaining part in coal was thiophenic sulfur.