Abstract: Copper foams with different pore densities were chosen as the substrate to deposit the continuous diamond film on the surface by chemical vapor deposition (CVD) technology. The influence of the pore density of the foam skeleton on the overall heat transfer effect of the diamond film was explained by finite element simulation. The scanning electron microscope, the Raman spectrum and the infrared thermal imager were used to compare and analyze the micro morphology, the film composition and the thermal diffusivity of diamond foam with different pore densities. The results show that high pore density foam substrate is more conducive to heat transfer, but its tiny pore size limits the flow of free radicals in the pores, and the size of diamond grains deposited by CVD is significantly reduced, with only 2~3 μm. The grain quality is also slightly inferior to that of medium and low pore density samples. In the infrared thermal imaging with the same heating time, the surface heating rate of the medium pore density diamond foam is higher than that of the high and low void density samples, which increases by 43.4% and 12.7%, respectively. In summary, the diamond foam with excellent three-dimensional connectivity and excellent diamond quality has excellent thermal conductivity, and is a better choice of heat conduction reinforcement.