Abstract: Biological effluent of petrochemical wastewater treatment plant contains toxic and refractory organic compounds, which is difficult to be furtherly treated by biological process. However, with the implementation of Emission Standard of Pollutants for Petroleum Chemistry Industry (GB 31571-2015) after July 1, 2015, the petrochemical wastewater treatment plants had experienced great centralized technology improvement. Meanwhile, most of the advanced treatment units have been built by ozone/catalytic ozonation process to achieve the discharge standard. At present, most of these advanced treatment units have been in operation for more than two years. With the actual operation, a series of problems which were not taken into account at the beginning of the design have arisen. Due to low ozone utilization rate and continuous deterioration, the treatment costs continuously increased. In order to solve these problems, combined with practical conditions, four aspects of the flocs, colloidal macromolecule organic compounds, ozone mass transfer and catalysts were analyzed. In the meantime, the development trend of ozone catalytic oxidation technology in secondary effluent treatment of petrochemical industry was put forward.