Copper-silver quasi-nano filamentary composites prepared by hot isostatic pressing followed by heavy drawing were irradiated in CT hole of a domestic experimental nuclear reactor, HANARO to study the morphological change of the poly-crystalline nano-filaments with irradiation and annealing conditions. The irradiation was carried out for 36 days at 320 o C with the maximum neutron flux of 4.8x10 20 n/cm 2 (E>1.0 MeV). The gamma heating rate was in the range of 2.0-6.45 W/gm. Polycrystalline silver nano-filaments of the composites were equilibrium shape like the faceted sphere shape. Annealing results in the increase of the faceting rate of the irradiated specimen. Nano-indentation results supported that the morphology change of nano-filaments by annealing in this study is more effective on strength change of the irradiated nano-filamentary composites than irradiated hardening.