Abstract: In order to investigate the effects of coal tar as co- processing reaction solvent,the structure changes of high- temperature coal tar before and after hydrogenation was characterized using analysis means such as1 H nuclear magnetic resonance spectroscopy and infrared spectroscopy. The average molecular formula and structure parameters of high- temperature coal tar before and after hydrogenation were calculated according to elemental analysis and average molecular weight data. Furthermore,high- temperature coal tar before and after hydrogenation were used respectively to conduct experiments with coal,the effects of high- temperature coal tar structure changes after hydrogenation on hydrogen donation capacity was studied by analyzing the product composition. The results showed that the average structure of high- temperature coal tar changed obviously after hydrogenation. Hydrogenation made part of the aromatic ring be replaced and side chains break,aromatic hydrogenation saturation formed hydrogenated aromatic hydrocarbons or other aliphatic structure by ring opening reaction. The aromatic hydrogen( HA) content decreased from 0. 743 to 0. 605,the Hα,Hβand Hγincreased by 0. 109,0. 022 and 0. 007.The PDQI index of high- temperature coal tar increased by 0. 68 after hydrogenation which indicated better hydrogen donation performance. The conversion ratio of raw material and oil yield raised by 1. 24% and 3. 92%. Preasphaltene and asphaltene yield decreased by 2.25%. The product composition of one ring to tetracyclic compounds increased by 0. 79%,0. 53%,2. 97% and 0. 83%. The H / C atomic ratio was enhanced from 0. 99 to 1. 33. The hydrogenation of coal tar for co- processing reaction promoted the transfer of heavy products to light products in co- processing reaction.