Abstract: The FeCl₃ supported on activated carbon was used as catalyst and oxygen as oxidant to form a heterogeneous catalytic wet oxidative system for the treatment of4-cholrophenol wastewater. By orthogonal experiments, the oxidation effect of 4-cholrophenol in the system was preliminarily investigated from the aspects oftemperature, oxygen pressure, reactive time and amount of FeCl₃/C. With 30%FeCl₃/C, under 0.5 MPa of O₂ and at 150 ℃, the intermediate products and final products in the degradation process were analyzed. The results showed that 67% 4-chlorophenol was destroyed with 39% COD_Cr reduction after 4 h. It was found that the introduction of NaNO₂ as the cocatalyst in the oxidative degradation systems brought about effective improvement on overall catalytic activity for the removal of 4-chlorophenol.