As a type of heat dissipation material, graphite has attracted great attention due to its outstanding thermal conduction. However, the relatively poor through-plane thermal conductivity restricts its applications in certain areas. In this work, a novel thermally conductive film was developed via in situ growth of Cu microparticles between interlayers of expanded graphite (EG). The intercalation of Cu microparticles in EG improved the through-plane thermal conductivity of the film from 8.5 to 11.1 W/(m K), owing to the three-dimensional stacking architecture of Cu/EG hybrid framework, which leads to more thermal paths along the vertical direction. This Cu/EG hybrid film showed better heat spreading ability than the pristine EG film, reducing the working temperature of the LED device by 1.9 degrees C. Furthermore, the through-plane thermal conductivities of Cu/EG hybrid films can be controlled by the amount of Cu precursors, and the highest through-plane thermal conductivity of 11.1 W/(m K) was achieved with intercalation of 0.8-4.5 mu m Cu microparticles by adding 50% Cu precursors. This thermally conductive Cu/EG hybrid film has great potential in the thermal management of electronic devices.