The effects of aging treatment on the microstructure and mechanical properties of Cu-10Fe-3Ag in-situ composite were investigated. And the mechanism of Ag element was analyzed during aging treatment. The results show that: presence of Ag can accelerate γ-Fe precipitation from in the Cu matrix, but also reduces the thermal stability of Fe fibers. As the aging temperature increasing, the hardness and conductivity of Cu-10Fe-3Ag in-situ composite increase at first and then decrease. The conductivity of Cu-10Fe-3Ag in-situ composite can reach 58.4% IACS when aging for 6h at 475 °C. The Fractures of the alloy are all ductile rupture and the dimples are smaller with the aging temperature increasing.