The invention discloses a high heat-conducting thin graphene-based composite material, as well as a preparation method and an application thereof. The composite material comprises a base body component and a packing component, wherein the base body component and the packing component respectively include thin graphene, polymer and/or polymer monomer and a high heat-conducting material; the preparation method comprises a step of compounding the base body component with the packing component; the compounding method comprises fusing, ball-milling, solution blending, electrostatic spinning, solution spinning, melt-spinning, extruding by double screws, mixing by an open mill or powder metallurgy. The polymer, the thin graphene, the traditional high heat-conducting material and the like are compounded by a simple process, so as to form the product with excellent heat conducting property, and good mechanical and electrical properties. Therefore, the process is easy to perform and control, and cost is low; and the obtained product has a wide application prospect in the aspects such as efficient heat conduction and radiation.