In this paper,a new and efficient way to oxidize and functionalize the multi-walled carbon nanotubes (MWNTs) has been developed by using a combination of ultraviolet (UV) irradiation and Fenton oxida-tion process,namely UV/Fenton oxidation treatment. Comparing with conventionally individual Fenton oxidation treatment of MWNTs,UV/Fenton combined treatment improved the etching rates and effi-ciencies and hence reduced the time for surface modification of MWNTs,which was proved to be an effective method in etching and functionalizing CNTs. The formation of new functional groups,struc-tural changes and thermal stability during oxidation period were characterized by Fourier transform infrared spectroscopy (FTIR),Raman spectroscopy and could be clarified by thermogravimetric analy-sis (TGA),which showed that it was under UV irradiation conditions that MWNTs could be rapidly functionalized with hydroxyl,carbonyl and carboxyl groups in the presence of Fenton reagents,origi-nating from the increase in the gross HO· concentration and the existent synergetic effect when using UV irradiation combing with Fenton oxidation process. Introduction of such new oxygen-containing functional groups was attributed to attacks of HO· on defect sites and unsaturated bonds of C=C in the MWNTs sample,which should play an important role in accounting for the FTIR and Raman spectral changes. In this paper, a new and efficient way to oxidize and functionalize the multi-walled carbon nanotubes (MWNTs) has been developed by using a combination of ultraviolet (UV) irradiation and Fenton oxida- tion process, in UV / Fenton oxidation treatment. Comparing with conventionally individual Fenton oxidation treatment of MWNTs, UV / Fenton combined treatment improved the etching rates and effi-ciencies and hence reduced the time for surface modification of MWNTs, which was proved to be effective method in etching and functionalizing CNTs. The formation of new functional groups, struc-tural changes and thermal stability during oxidation period were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and could be clarified by thermogravimetric analy- sis (TGA), which showed that it was under UV irradiation conditions that MWNTs could be rapidly functionalized with hydroxyl, carbonyl and carboxyl groups in the presence of Fenton reagents, origi-nating from the incr ease in the gross HO · concentration and the existent synergetic effect when using UV irradiation combing with Fenton oxidation process. Introduction of such new oxygen-containing functional groups was attributed to attacks of HO · on defect sites and unsaturated bonds of C = C in the MWNTs sample, which should play an important role in accounting for the FTIR and Raman spectral changes.