Abstract The interface and its effect on the thermal conductivity and bending strength of SiC/Al composite were investigated. The results indicated that the compact interfacial layer could be obtained when holding the SiC particles for 4h at 1200°C. The decrease of the holding time reduced the thickness of the interfacial layer, yet harmful for the thermal transfer of the interface due to the formation of pores and Al4C3. The prolongation of the holding time introduced SiO2 layer owning the very low instinct thermal conductivity, resulting in the increase of interfacial thermal resistance. However, the addition of SiO2 layer seems less harmful for the interfacial thermal transfer with respect to the thin SiO2 layer. The critical thickness of SiO2 layer is confirmed to be 210nm. Very similar to the variation of thermal conductivity, the bending strength follows a first increase until reaches a maximum value 435MPa and then trends to decrease. The composite after T6 treatment exhibits a better bending strength compares to T2 treated composite.