Abstract: In order to meet the new environmental protection requirements and further improve the treatment level of coking wastewater,the coking wastewater treatment system of a plant in Panzhihua has been upgraded and optimized.The advanced purification treatment of wastewater has been strengthened by using ozone catalytic oxidation technology.Through the optimization of influent suspended solids,thiocyanate and hydraulic retention time,the operation and treatment capacity of the system has been greatly improved.The water quality is better than that of the direct discharge standard in Table 2 of GB16171—2012,with the amount of ammonia and nitrogen ≤ 1 mg/L,COD ≤ 70 mg/L.It presents an obvious effect in removal of polycyclic aromatic hydrocarbons and benzopyrene,with the color of the water obviously improved,indicating a well industrial operation effect.