Abstract: In view of the problem that the heat dissipation capacity of traditional aluminum alloy heat sinks has gradually reached a bottleneck, this paper studies the "sandwich" graphite-aluminum composite material configuration, and uses comparative tests to verify the lateral heat dissipation advantages of this configuration compared with aluminum alloy. Using the established simulation model, the lateral and longitudinal thermal conductivities of the graphite layer and graphite-aluminum material are quantified by using the semi-physical measurement and correction method. The research results show that the transverse thermal conductivity of graphite aluminum is 390 W/(m·K), its heat dissipation capacity is close to that of copper, but its density is much lower than that of copper, so it has obvious application advantages in the lightweight engineering of aerospace products. The thermal conductivity of the graphite layer obtained in this paper can guide thermal designers to obtain solutions that meet the design requirements according to different design plan requirements and rely on simulation software.