Abstract: To improve the thermal conductivity of epoxy (EP) with a lower thermally conductive filler content, graphene nanoplates/(polyetherketone cardo-EP) (GNP/(PEK-C-EP)) composites were prepared by the solution method. The selective distribution of GNP was predicted by calculation based on contact angle measurements, and the effects of GNP and PEK-C contents on the microstructures and thermal conductivities of GNP/(PEK-C-EP) composites were investigated by SEM and laser flash method. The results show that double percolation structures are formed in GNP/(PEK-C-EP) composites as the content of PEK-C reaches 20wt%, where GNPs are selectively distributed in PEK-C to build continuous heat conduction paths. For GNP/EP composites, it reaches the highest thermal conductivity of 0.375 W(m·K)⁻¹ at 1wt% GNP. While for GNP/(PEK-C-EP) composites, the content of 0.5wt% GNP reaches highest thermal conductivity of 0.371 W(m·K)⁻¹, which is 48% higher than that of GNP/EP composites at 0.5wt% GNP content and basically the same as that of GNP/EP composites at 1wt% GNP. It indicates that the filler content of GNP/(PEK-C-EP) composites is reduced by 50% owing to the double percolation effect. In addition, the glass transition temperatures, thermal stability and coefficients of thermal expansion of pure EP and GNP/(PEK-C-EP) composites were compared. The results show that the GNP/(PEK-C-EP) composites are superior to pure EP in thermal properties.