Abstract: Copper hydrosol were prepared from the solution of copper nitrate with NaBH4 by reductive reaction in water and ethanol-water system in the presence of NaOH and CTAB,and the copper hydrosol were transferred into organic phase by the addition of PAMDTCD.FTIR,TEM,XPS and XRD were utilized to investigate the structure and stability of copper nanoparticles modified with PAMDTCD.The results showed that the modified copper nanoparticles are stable in ambient conditions,which is attributed to the protection of the PAMDTCD molecular densely packed on the copper surface.