The toluene soluble of coal tar pitch was carbonized with waste polystyrene. The properties of mesophase pitches were characterized using polarized light optical microscope, apparent viscometer, FT-IR, H-1 NMR and X-ray diffractometer. After adding the waste polystyrene into the toluene soluble of coal tar pitch, the soluble mesophase were was increased from about 9% to 52% and the mesophase pitches were changed from 74% with coarse mosaic texture to 100% with flow domain texture. The mesophase pitches were transformed from thixotropy to unthixotropy. By waste polystyrene added into the toluene soluble of coal tar pitch, the methylene group was increased a lot. The presence of more alkyl groups modified the characteristics of mesophase pitches and improved the assembly of mesophase pitch molecules. (C) 2008 Elsevier B.V. All rights reserved