Commercial　activated　carbon　fiber　(ACF)　has　been　employed　as　particle　electrodes　to　degrade　aqueous　m-cresol　in　3-D　electrode　systems.　To　enhance　the　electrooxidation　performance,　three　types　of　new　ACF　modification　modes　(anodic　oxidation,　cathodic　reduction,　and　aqueous　oxidation　with　concentrated　HNO3)　were　introduced　in　this　paper.　These　pretreated　samples　were　characterized　by　N-2　adsorption,　scanning　electron　microscopy　(SEM),　cyclic　voltammetry　(CV),　temperature-programmed　desorption　mass　(TPD-MS),　X-ray　photoelectron　spectroscopy　(XPS),　and　Fourier　transform　infrared　spectroscopy　(FT-IR).　It　was　revealed　that　the　two　new　modification　methods　could　efficiently　modify　the　surface　morphology　as　well　as　the　chemical　property.　Eight　types　of　surface　oxygen　groups　(SOGs)　were　identified　on　the　surface　of　ACF,　and　the　types　and　amount　of　SOGs　might　be　related　to　the　oxidation　effect　of　ACF　on　the　3-D　electrodes.　The　effect　and　mechanism　of　these　SOGs　on　electrooxidation　performance　were　discussed　with　the　aid　of　the　frontier　molecular　orbital　theory.　It　was　demonstrated　that　the　H2O2-OH　reaction　mechanism　was　improved　in　the　3-D　electrode　system　and　the　mechanism　was　elucidated.