Abstract: FEP-based composites filled with alumina platelets were prepared by the physical blending method. The thermal conductivity and elongation of the composites containing Al₂O₃ platelets were studied in comparison with Al₂O₃ particles as filler. The microstructure of the composites was also observed by SEM. The results show that the Al₂O₃ fillers with low mass fractions display an island distribution in the FEP matrix and cannot form the continuous thermal conduction chains. However，the thermal conductivities of the composites greatly increase compared with the single FEP. The tensile strength and the elongation at break of the composites decrease with the increase of the Al₂O₃ content . The increasing thermal conductivity of the composites containing fine alumina platelets is associated with the prolonged heat conducting path and the interface between the fillers and FEP.