Abstract: Thermally conductive polyamide 6 (PA6)-based composites were prepared through a melt-blending method by use of expanded graphite (EG), boron nitride (BN), Al2O3, and zinc oxide whiskers (T-ZnOW) as functional fillers, and effect of filler shape on thermal conductivity of the composite was investigated. Furthermore, EG was used as a major thermally conductive filler to compound respectively with BN, Al2O3 and T-ZnOW so as to confirm the role of filler type in the improvement of thermal conductivity of the composites. The results indicate that EG had a better enhancing effect on the thermal conduction of PA6 matrix than the other three. As a small-size filler, Al2O3 can help to open the layers of the lamellar EG, thus forming a more perfect thermally conductive network and leading to a better synergistic effect accordingly. PA6-matrix composites achieved a maximum thermal conductivity of 3.05 W/(m·K) by 7.5 vol % of BN, 3.10 W/(m·K) by 5 vol % of Al2O3 and 2.84 W/(m·K) by 2.5 vol % of T-ZnOW in the mixed fillers with a total volume fraction of 20 vol %.