Abstract: Given the problem of air pollution during the impregnation-calcination catalyst preparation process, it is of great significance for practical application to study and develop a method of catalyst preparation that avoids the production of nitrogen oxides and sulfur oxides. In this paper, the co-blending method was used to prepare the catalyst without using nitrates, sulfates, etc., so as to avoid the generation of nitrogen oxides and sulfur oxides. The removal efficiency of pollutants from petrochemical secondary effluent by catalytic ozonation was studied with the prepared catalysts. Experimental results show that in terms of the catalysts prepared by co-blending method, the Mn/Al₂O₃ catalyst showed higher catalytic activity in catalytic ozonation of secondary effluent from petrochemical wastewater compared with other catalysts loaded with single active component; the Mn-Cu/Al₂O₃ catalyst had a better removal effect than other catalyst loaded with dual active components on catalytic ozonation of biochemical effluent from petrochemical wastewater, whose TOC, COD and UV₂₅₄ removal rates reached 34.54%, 49.53% and 56.81%, respectively and the removal rate of humic-like substances in fluorescent substances was 71.64%. Catalysts of the same component was prepared by co-blending method, excessive impregnation method and equal volume impregnation method, respectively, and the excessive impregnation method presented the highest catalytic activity, followed by the co-blending method, while all treated effluents met the emission limits in the Emission Standard of Pollutants in Petrochemical Industry (GB 31571-2015). The preparation of ozone catalyst by co-blending method can effectively avoid the harm to the environment during the impregnation calcination process, and show high catalytic activity in the catalytic ozonation treatment of secondary effluent of petrochemical wastewater. This study can provide technical support for the actual production and application of environmentally friendly catalysts.