Abstract: A temperature-programmed tube furnace was set up to investigate the occurrence modes of mercury in coal according to its releasing temperature during pyrolysis. The fraction of mercury in each occurrence mode was determined by calculating the total released amount at different temperature ranges. The mechanism of mercury release inhabitation by CaCl₂ was studied as well. The result showed that there are mainly three occurrence modes of mercury in coal: their release temperatures are 220, 300 and 400 ℃.The secondary mode released at 300 ℃ takes 54.18%, which should be HgS according to its decomposition temperature. The CaCl₂ inhibited the release of mercury at 220 and 400 ℃. The inhabitation is mainly caused by mercury oxidation and adsorption. By adding CaCl₂, the mercury release is focused to a certain temperature but the total release amount is hardly influenced.