Abstract: Surface modification of multi–walled carbon nanotubes (MWCNTs) by wet chemical oxidation, then, further processing by solvothermal method to prepare magnetic multi–walled carbon nanotubes (6O-MWCNT/Fe₃O₄) with excellent heavy metal adsorption performance. SEM, FT–IR, XPS and other characterization results show that the surface of MWCNT modified with magnetic ferric oxide surface has effectively introduced oxygen–containing functional groups (—COOH and magnetic Fe—O groups). The prepared 6O-MWCNT/Fe₃O₄ combines the excellent characteristics of MWCNT materials and the magnetic characteristics of Fe₃O₄ magnetic materials. On this basis, 6O-MWCNT/Fe₃O₄ is used as a reliable adsorbent for heavy metal water treatment. Experimental results point out that 6O-MWCNT/Fe₃O₄ has a good adsorption and separation effect on Cu(II), Cd(II) and Pb(II), The optimum adsorption pH is 6, and the maximum saturated adsorption capacity is 87.64, 57.14, 215.05 mg•g^–1. At the same time, we also found that the material is selective for coexisting ions. By fitting the adsorption kinetics curve, it was found that the material conforms to the Langmuir adsorption isotherm model and the pseudo–second–order kinetic adsorption model. This study provides a new thinking for the treatment of heavy metal ions in water bodies by adsorption.