Abstract: Conversions of 3 coal tars and their fractions in supercritical water (SCW) were investigated using a batch reactor. The results indicate that the conversion of the coal tar which has the highest content of asphaltene can obtain more lightproduct compared with the other two coal tars. It is also noticed that asphaltene is the main active component and it converts to maltene, gas and char in SCW. Compared with pyrolysis in N2, the conversion of asphaltene to maltene is enhanced while the formation of gas and char is restrained in SCW. Based on analysis of pyrolysis product, it is deduced that aromatic nucleus of asphaltene molecule is mainly composed of 1～4 rings aromatic compounds. Moreover, less than 10% of maltene fraction converts to gas, asphaltene and char. The fraction of char is very stable in SCW. Reaction pathway of coal tar in SCW is proposed from the reaction property of each fraction.