Nano-Cu/Al2O3 assemblies were prepared by AC electrochemical deposition of Cu in the ordered pores of alumina membranes. TEM measurement show that the amount of Cu nanoparticls increase with the deposition time. Optical absorption characteristics in the wavelength range 200—800nm has been investigated for the assemblies, and only an absorption band-edge was observed. With the increasing deposition amount of Cu, the absorption band-edge red-shifts. The results are discussed in terms of Rayleigh scattering. Meanwhile the assemblies exhibit the optical features of a semiconductor with indirect band gap.