A new kind of the micron-sized flaky silver-coated copper powder was prepared by electroless silver plating in this paper. Its plating structures were characterized by XRD, SEM and EDS. And a new kind of the electromagnetic shielding composite coatings containing 60 wt% the micron-sized flaky silver-coated copper powders and 40 wt% epoxy resin was prepared. Its electromagnetic shielding properties were analyzed by coaxial transmission line equipment. The study results show the micron-sized flaky silver-coated copper powders are composed of 91.35 wt% Cu and 8.65 wt% Ag and have high width-thickness ratio and crystal structure characteristics. In the frequency range of 0.3-1000 MHz, the shielding effectiveness of the coatings is up to 70.15-77.46 dB and increased an average of 22.18 dB compared with the coatings containing 60 wt% micron-sized flaky copper powders when the coating layer thickness is 300 μm. It is seen that the electroless silver plating method effectively improves the inoxidizability, conductivity and electromagnetic shielding properties of copper powders.