Abstract: To improve the removal efficiencies of chemical oxygen demand (COD), chromaticity and ammonia nitrogen, different reaction conditions, such as O₃ ventilation, Na₂S₂O₈ dosage, pH and reaction time were researched by experiments. The experiment results show that the removal rates of COD, chromaticity, and ammonia nitrogen increase with the increase of O₃ ventilation, Na₂S₂O₈ dosage, pH value, and reaction time. Under the conditions of Ozone ventilation of 0.8 g/h, Na₂S₂O₈ dosage of 10 g/L, pH 10, and reaction time of 200 min, the removal rates of COD, color, and ammonia nitrogen removal attain 76.3%, 92% and 55.4%, respectively. The persulfate oxidation process added by O₃ has better treatment efficiency on the landfill leachate biochemical effluent than that of single oxidation in the treatment. It suggests that a synergistic effect happens between the O₃ oxidation and Na₂S₂O₈ oxidation.