Supercritical toluene solubles in isotropic coal tar pitch is extracted at conditions of 330℃, and 50 bar, 70 bar, and 90 bar,respectively. Benzene and quinoline insoluble contents, C/H atomic ratio, and softening point of extraction residues were increased by the extraction residues were increased by the extraction of supercritical toluene solubles. β-resin content in extraction residues increased as extraction and the maximum value is reached at about 10wt% in the experiment conditions. Mesophase formation rate in thermal treatment of extraction residues is in parallel with extraction amount, and it shows the modification of carbonization properties of isotropic coal tar pitch by extraction of solubles with supercritical toluene.