After secondary biochemical treatment, the COD, BOD and NH3-N of the landfill leachate can not reach the leachate emission standard. Using ozone oxidation-upflow biological aerated filter (UBAF) for advanced treatment, the COD's removal ratio could be increased accordingly with the addition and reaction time of ozone in a certain range. With the influent flow velocity of 160 cm.s(-1), the removal ratio of UBAF was optimal. Under the optimal conditions, in 12 days, treated by ozone-UBAF, the removal ratio of leachate's COD and NH3-N was 68.9-74.6 % and 59.6-66.6 % respectively. Influent leachate mainly contains 35 kinds of organic pollutants. After treated by ozone oxidation-UBAF, 16 organic pollutants in the leachate can be completely removed, the removal ratios of 7 kinds of organic pollutants were 77-96 % and the removal ratios of the other 7 kinds of organic pollutants were 6-43 %. However, 5 kinds of organic pollutants' concentration were increased instead of decreased. 3 kinds of organic pollutants were newly generated due to the chemical reaction in the process of the ozone oxidation.