Abstract: Polyethylene glycol-200 and-400 were used to modify coal-tar pitch using p-toluene sulfonic acid as a catalyst. The chemical properties of the modified pitches and the microstructure of the derived cokes were studied. Results showed that the β resin contents were increased by 52-55 wt.%, the residual carbon yield at 800℃ was increased by 18 wt.%, the vibration absorption frequency of bond in aromatic rings increased significantly, and the condensation degree was improved after the modification. The modification reactions occurred at the positions of aromatic hydrogen. The viscosities of the pitch modified with PG-400 and-200 are respectively lower and higher than that of the pristine pitch. The fibrous structure of the semi-coke from the PG-200 modified pitch was significantly improved and its degree of ordering and stack height of graphene layers were also increased significantly.