Cu-24wt%Ag alloy sheets were prepared by cold rolling and aging to reveal the evolution of microstructures, mechanical properties and electrical conductivity. The connection between the strengthening, conductivity and microstructure refinement of the alloy was discussed. After severe cold rolling, the microstructure develops into nano-layered structure of Cu and Ag arranged alternatively, with numerous Ag nano-fibers embedded in Cu matrix and (Cu+Ag) eutectics distributed in Ag areas. Shear bands occur in longitudinal sections as the strain reaches 94% or so. With increasing the rolling strain, spacing of Cu/Ag interface, Ag fibers and eutectic lamellae decreases gradually to nanoscale, leading to significant enhancement of the strengthening effect, and hence the hardness increases rapidly when the strain exceeds 96%. The relationship between the resistivity increment caused by Cu/Ag interface and rolling reduction was established, reflecting the influence rule of microstructure refinement on electrical conductivity in the rolling process.