Abstract: With nylon 6 (PA6) as the matrix and carbon fiber (CF), expanded graphite (EG) as the thermal conductive filler, EG/PA6, CF/PA6 and CF-EG/PA6 thermal conductive composites were prepared by melt-mixing. Fixed the filling content of 40wt%, the effects of different ratios of CF to EG on the contact mode between CF and EG, and the thermal conductivity and mechanical properties of CF-EG/PA6 composites were studied. The results indicate that the addition of EG is beneficial to increase of the thermal conductivity of CF-EG/PA6 composites compared to single CF filling; When CF:EG mass ratio is 25:15, the thermal conductivity of CF-EG/PA6 composite reaches 2.554 W/(m·K), which is 7 times higher than that of PA6, the tensile strength is increased by 125.34%, the flexual strength is increased by 119.8%, and the heat resistance demonstrates excellent. The SEM results show that fibrous CF and worm-like EG can form a 3D network structure with "Terms contact" under the appropriate filling ratio. The 3D network structure not only significantly increases the thermal conductivity of CF-EG/PA6 composite, but also significantly improves the mechanical and thermal properties of the composite. It provides a new idea for the development of filled thermally conductive polymer materials.