Cu/Ag core-shell powders have been prepared by liquid phase reduction reaction using ascorbic acid as a reducing agent through inhibiting substitution reaction. The composition and the content for the pretreated and coated copper powder, the morphology and the particle size distribution of Cu/Ag core-shell powders, the composition of the coated-surface were characterized by XRD, SEM, EDS, TAG and laser particle analyzer, etc. The results show that a continuous silver film is formed on the surface of copper powder by coating for a time. The observed Cu/30%Ag (mass fraction) powder has a good oxidation resistance and thermal stability. The paste prepared with ready-made silver powder and Cu/30%Ag were printed on the silicon，and the square resistance of the sintered film tested by four-point probe is 12.35 mΩ/□, indicating the electrical property of the prepared Cu/Ag core-shell powders is qualified for solar cell．