Electromagnetic shielding plastics with different mass fractions were prepared by melt blending three kinds of silver-coated copper powder (Ag@Cu) with ethylene-vinyl acetate copolymer (EVA). The effects of different mass fractions and particle sizes of Ag@Cu on the electrical conductivity, shielding properties and mechanical properties of EVA-based electromagnetic shielding plastics were investigated. EVA-based electromagnetic shielding plastics were toughened by maleic anhydride grafted ethylene-octene copolymer/ethylene-octene copolymer (POE-g-MAH/POE) toughening masterbatch and polyisobutylene (PIB)/terpene toughening masterbatch, respectively, to obtain highly filled electromagnetic shielding plastics. The results show that with the increase of Ag@Cu content, the electrical conductivity of EVA-based electromagnetic shielding plastics increases, while the mechanical properties decrease. The percolation threshold of the composites decreases with the increase of filler particle size. When the Ag@Cu filling content is 80%, the shielding effectiveness increases with the increase of filling particle size. Compared with POE-g-MAH/POE, the toughening effect of PIB/terpene is the best, the elongation at break is increased to 187.3%, the shielding effectiveness is kept above 70 dB in the range of 30~1 000 MHz, and it shows better extrusion processability.