In　this　study,　Multiwalled　carbon　nanotubes　(MWCNTs)　were　oxidized　by　a　mixture　of　sulfuric　acid　and　nitric　acid　(V:V　=　3:　1)　at　70　degrees　C　for　1,　2,　and　4　h,　respectively.　The　oxidized　MWCNTs　were　characterized　by　N-2　adsorption,　Fourier-transform　infrared　spectroscopy　(FT-IR),　X-ray　photoelectron　spectroscopy　(XPS),　thermal　gravimetric　analysis　(TGA),　and　Raman　spectroscopy　to　determine　the　oxidation　degree.　The　dispersion　of　the　MWCNTs　was　investigated　by　UV-vis-NIR,　SEM,　and　dynamic　light　scattering　measurements.　Results　show　that　sulfonitric　treatment　increased　the　surface　area　and　total　pore　volume　and　reduced　the　average　pore　diameter　of　MWCNTs.　The　treatment　promoted　the　formation　of　oxidized　species　on　the　surface　MWCNTs,　as　identified　by　FT-IR,　TGA,　and　X-ray　photoelectron　spectroscopy　measurements,　and　more　oxygen-containing　functional　groups　were　generated　when　treatment　time　was　extended.　Moreover,　a　general　relationship　between　oxidation　degree　and　dispersibility　of　MWCNTs　in　water　was　established.　UV-vis-NIR　and　dynamic　light　scattering　measurements　and　SEM　images　revealed　that　MWCNTs　with　higher　oxidation　degree　showed　better　dispersibility　in　water.