Abstract: To improve the low longitudinal thermal conductivity of graphite film/aluminum composites, this study employed high-thermal diamond to penetrate the aluminum layer and establish a thermal conduction channel within the composites to effectively enhance their longitudinal thermal conductivity. To enhance the interface bonding between diamond and aluminum matrix. Tungsten coating was applied on the diamond surface using physical vapor deposition (PVD) technology. Subsequently, diamond-reinforced graphite film/aluminum composites were fabricated through fast hot pressing sintering (FHP) method. The influence of interfacial bonding and diamond volume fraction on the thermal conductivity of the composite were investigated. The results demonstrate that at a 10vol% volume fraction of W-coated diamond, the in-plane thermal conductivity reaches its peak value at 658 W/(m·K), which is 7% higher than that of an uncoated corundum reinforced composite. However, when the volume fraction of tungsten diamond plating exceeds 10vol%, the in-plane thermal conductivity shows a decreasing trend. The in-plane thermal conductivity is reduced to 535 W/(m·K) for composites with a high volume fraction of tungsten diamond coated (30vol%). Nevertheless, as the diamond volume fraction increases, more thermal conduction channels are formed within the composite leading to an increase in longitudinal thermal conductivity up to its highest value at 177 W/(m·K), which is 34% higher than that of uncoated diamond reinforced composites. The present study demonstrates that the incorporation of diamond thermal conduction channels between graphite film and aluminum effectively enhances the longitudinal thermal conductivity of composites.