The invention relates to a core-shell-structured silver-based heat-conductive rubber composite material and a preparation method thereof. The composite material comprises a rubber matrix, a vulcanizerand core-shell-structured silver-based heat-conductive filler. The core-shell-structured silver-based heat-conductive filler is prepared through subjecting dopamine to self-polymerization on the surface of high-heat-conductivity inorganic filler so as to form a polydopamine functional layer, putting the heat-conductive filler, of which the surface is coated with a polydopamine layer, into a silver plating solution, adding a reducer glucose solution, and depositing and coating the surface of the high-heat-conductivity inorganic filler with silver nanoparticles by an in-situ chemical reductionmethod. The rubber composite material with high coefficient of thermal conductivity and low dielectric constant is prepared through adding the core-shell-structured silver-based heat-conductive fillerinto the rubber matrix. The composite material is excellent in heat-conducting property and can be applied to electronic packaging materials. The preparation method is simple, convenient, effective and controllable in operation and is economical and environmentally friendly.