Fabricating high-k conductor/polymer composites with low dielectric loss and percolation threshold is still a challenge, while the electric conductor is the key factor of determining the dielectric behavior of composites. A novel hybridized conductor with "sandwich" structure (rPANI@CNT-rGO) and active groups was prepared by introducing polyaniline coated carbon nanotube (rPANI@CNT) on the surface of reduced graphene oxide (rGO) through electrostatic and pi-pi conjugate forces. And the rPANI@CNT-rGO hybrids with different loadings of rPANI@CNT were introduced into epoxy resin (EP) to prepare a series of [email protected]/EP composites; meanwhile rPANI@CNT and rGO were mechanically blended with EP to prepare rPANI@CNT/0.75rGO/EP composites for comparison. rPANI@CNT/0.75rGO/EP composites have low dielectric constant (10-20), whereas the dielectric constant at 100 Hz of the [email protected]/EP composite with 0.75 wt% rPANI@CNT is as high as 210, much larger than those of rPANI@CNT/EP, 0.75rGO/EP and rPANI@CNT/0.75rGO/EP composites. Meanwhile, the dielectric loss at 100 Hz of [email protected]/EP composite is only 17% of that of 0.75rGO/EP, indicating that the dielectric behavior of [email protected]/EP composites is not originated from a simple addition of basic components, but has an obvious synergistic effect. The percolation threshold of [email protected]/EP composites is only 1.1 wt%. The origin of these attractive dielectric properties was revealed through systematically discussing the structures and simulated circuits of [email protected]/EP composites. (C) 2015 Elsevier B.V. All rights reserved.