Abstract: The decoration of carbon nanotubes with amine groups by reacting with diamine was investigated by TEM, FT-IR and Raman spectroscopy after multi-walled carbon nanotubes (MWNTs) synthesized by chemical vapor deposition (CVD) had been purified and oxidized to contain carboxylate groups. It is found that the ends and side-walls of MWNTs are opened and oxidized into carboxylate group (σ(C=O)＝1709cm-1), and the amide-alkyl chain appears on the derivatives of the MWNTs (σ(C=O)＝1581cm-1) and the solubility of MWNTs in organic solvent is enhanced. The Raman results show that the D line and G line of MWNTs have no obvious changes before and after the reaction, which indicate that MWNTs retain their structure after the condensation reaction.