Abstract: Terephthalic acid (TPA) can be obtained in the presence of Zn(Bzo)2 by isomerization of potassium salt of coal acid (water soluble acids, WSA) with organic dispersant having high boiling point in slurry reactor. The effects of initial CO2 pressure, amount of catalyst, reaction time, reaction temperature and the amount of dispersant on the yield of TPA were examined. The optimum conditions of isomerization, with TPA yield of 24.1%, using biphenyl as the dispersant were: temperature 420℃, initial CO2 pressure 3MPa, addition of Zn(Bzo)2 3%, dispersant 60% and reaction time 1h. The optimum conditions, with TPA yield of 25.2%, using pterphenyl as the dispersant were: temperature 380℃, initial CO2 pressure 1MPa, addition of Zn(Bzo)2 3%, and dispersant 60%. The yield of TPA by isomerization of mixture of potassium salts of coal acid and benzoic acid were 60% (use biphenyl as the dispersant) and 62% (use pterphenyl as the dispersant), respectively. The products were analyzed by gas chromatography.