Abstract: The critical properties of both binary and ternary mixtures involved in the toluene disproportionation were measured by using a high-pressure view cell with visual observation. Moreover, the critical properties of the ternary mixture were determined with the compositions representing reaction proceeding extent of toluene disproportionation. Based on that, toluene disproportionation over HZSM-5 catalysts under near critical and high temperature was comparatively studied. It was found that both the catalyst stability and the selectivity of para-xylene under near critical conditions in toluene disproportionation were higher than those under high temperature. The conversion of toluene increased with the temperature, but the selectivity of para-xylene decreased with the increase of temperature. The pressure has little effect on the selectivity of para-xylene at high temperature, but the conversion of toluene increased with the pressure.