Abstract: A kind of high temperature coal tar was selected as an experimental raw material. The thermal reaction at hydrogen atmosphere was carried out under the different contents of solid particles in an autoclave reactor. Then the coke was separated from reaction product. The solid particles and the coke were characterized and analyzed by X-ray diffraction,X-ray photoelectron spectroscopy,FT-IR,UV-VIS and scanning electron microscope. Results showed that a higher quantity of asphaltenes was obtained after a thermal reaction with an appropriate amount of solid particles,while the amount of secondary toluene-insoluble decreased significantly. The surface matter of the solid particles was mainly organic compounds,containing about 7% polar oxygen groups and 1. 4% polar sulfur and nitrogen groups. Due to the strong adsorption ability of solid particles to the asphaltenes,the asphaltenes in the coal tar exhibited a high dispers- ibility and was uneasy to be condensed to coke. Besides,the particle size of suspended coke was relatively small,exist- ing in the reaction system in a high dispersion,with comparatively little depositional coke at the bottom of autoclave.