Abstract: The damping properties and damping mechanism were investigated for SiC_P/ZL104 composite foams, fabricated by the method of direct melt foaming. The results show that under the conditions of the same pore-diameter, the loss factors of SiC_P/ZL104 composite foams are non-linear rising with the increase of porosity at the ambient temperature, and the incremental changes lessen gradually. The damping properties of SiC_P/ZL104 composite foams are better than those of foam aluminum, SiC_P/ZL104 composites and ZL104 alloy. The loss factors of SiC_P/ZL104 composite foams increase with the increase of the content of SiC_P and the decrease of granularity of SiC_P. Pores and high density dislocations in SiC_P/ZL104 composite foams contribute to their damping properties.