The secondary effluent of the chemical industry park contains a variety of toxic pollutants, which still poses a great risk to the ecological environment. In this study, the microbubble O₃/H₂O₂ process was established for advanced treatment of secondary effluent from a chemical industry park, and the operation parameters, pollutant degradation mechanism and toxicity evaluation were studied. The best operating parameters were pH 7.3, ozone dosage 60 mg/L, H₂O₂ initial dosage 114 mg/L, reaction time 15 min. Under this condition, the removal rates of COD and TOC were 47.41% and 46.61% respectively in microbubble O₃/H₂O₂ process. The microbubble O₃ can significantly improve the ozone utilization efficiency and shorten the reaction time. Compared with ordinary O₃ aeration, the ozone utilization rate increased by 10% and the reaction time shortened by two thirds. The removal process of organics by microbubble O₃/H₂O₂ process followed the apparent second-order reaction kinetics; the electron paramagnetic resonance (EPR) technology proved that hydroxyl radical (·OH) played a role in the degradation of organic substances, H₂O₂ promoted the formation of ·OH and microbubbles aeration promoted the production of more ·OH by O₃/H₂O₂ through the process. Dissolved organic matter had the tendency of transforming macromolecular substances into small molecular substances in the process of advanced treatment. H₂O₂ can enhance the removal ability of ozone to hydrophobic neutral components and change the degradation path of ozone to pollutants. Compared with 100% luminescence inhibition rate of microbubble O₃, the luminescence inhibition rate of microbubble O₃/H₂O₂ was less than 20%, suggesting that the addition of H₂O₂ can effectively inhibit the increase of acute toxicity.