The interfacial area increases with the drawing strain and the dislocation generated during deformation processing are deposited at the interface to relieve the mismatch across the interface. In this study, the interfacial structures of Cu-Nb nanocomposites in the as drawn and annealed condition were examined. The texture of Cu matrix and Nb filaments were not appreciably influenced by annealing in Cu-Nb processed by severe plastic deformation. At the matrix/filament interface, misfit interface dislocations were introduced periodically to relieve the misfit strain in the cold drawn Cu-Nb. Extensive spheroidization of Nb filaments took place after annealing, which made difficult to examine the interracial structure after annealing. After annealing above 500 degrees C, the amorphous layer was observed along the interfaces and amorphization became more extensive with increase of temperature. The amorphization at high temperatures is likely to contribute to the residual stress relaxation at the interface in the Cu-Nb nanocomposites..