Abstract: The effect of temperature on thermal dissolution of Hongliulin coal (HL),which was carried out in the solvent of n-hexane,was studied.The results showed that the small molecular compounds extracted from coal (including tar and water) increased from 7.10% to 11.96% as the temperature raised from 260℃ to 340℃.Thermal dissolution had a significant influence on the pyrolysis of HL.The volatiles separated from coal pyrolysis reduced from 28.02% to 10.49%~21.38%.As the dissolved temperature increased from 260℃ to 340℃,the pyrolysis volatile materials from extracted residue decreased significantly from 21.38% to 10.49%.Yield of products in liquid reduced from 12.01% to 3.72%,and those in gas decreased slightly.Small molecules in coal were "active" materials in the process of coal pyrolysis at low temperature,which not only belonged to pyrolysis liquid product,but also promoted the transformation of coal to tar or gas by providing hydrogen to the main structure of coal.