Abstract: The effect on landfill leachate treatment was studied by catalytic wet peroxide oxidation (CWPO) with H₂O₂ as oxidant and activated carbon fiber modified by concentrated nitric acid as catalyst. The removal rate of COD reached 88.95% at the optimal condition when the reaction temperature was 200℃, equivalence ratio of H₂O₂ was 1.8, the catalyst concentration was 4 g/L, and the reaction time was 120 min. Meanwhile, the refractory organics in leachate was degradated effectively after the CWPO processing through the analysis of UV-vis spectra and 3DEEM.