To impart conductivity and improve the shear performance of epoxy resin-based adhesives, a simple, environmentally friendly, and stable method was used to deposit silver on the surface of 5 μm flake copper particles as a conductive filler. The core–shell metal fillers were prepared by utilizing the autocatalytic properties of Cu without adding any reducing agent during the reaction. An epoxy curing agent (MeTHPA) was used as a curing agent for the crosslinking reaction with epoxy resin to form a supporting skeleton of conductive components. The structure of flake plated Cu@Ag particles was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). It was verified that a layer of compact and crystalline silver with a concave–convex characteristic was deposited on the surface of copper particles. This feature has a positive effect on improving the performance of silver-plated copper particles. The results show that the optimal curing condition of flake plated Cu@Ag particle–epoxy composite electrically conductive adhesives (ECAs) was 200 °C for 1 h, the resistivity of flake plated Cu@Ag particle–epoxy composite ECAs with a content of flake plated Cu@Ag particles above 55 wt% was less than 6 × 10⁻⁵ Ω m, and the maximum shear strength was 8 MPa. The flake plated Cu@Ag particle–epoxy composite ECAs prepared by this method have excellent properties and have very important application value for advanced electronic devices.