Abstract: The effects of the volume fraction and orientation of flake graphite on the thermal conductivity of graphite/6061 aluminum composite were studied by finite element method. A composite model of the directional arrangement and distribution of flake graphite with high volume fraction was established. The numerical simulation results were compared with the reference test results. The theoretical calculation of thermal conductivity was also performed by using the thermal conductivity model of composite materials. The results show that with the increase of the volume fraction of the flake graphite,the x-y plane thermal conductivity of the graphite/6061 aluminum composite increases, the thermal conductivity of the graphite composite with the volume fraction of 70% reaches 765.48 W/（m·K）, while the z-plane thermal conductivity decreases. The larger the orientation angle of the flake graphite is, the smaller the x-y plane thermal conductivity is. When the orientation angle is 0°-30°, the z-plane thermal conductivity first increases and then decreases with the increase of the orientation angle. The orientation angle of the graphite sheet should be controlled not to exceed 30°, and the thermal conductivity of the composite material is better. The simulation results of x-y plane thermal conductivity of composites with different flake graphite volume fractions are consistent with the experimental results, and the theoretical thermal conductivity calculated by considering the interface thermal resistance is close to the experimental results.