Abstract: Macroscopic graphite particulate reinforced commercially pure aluminum matrix composites were prepared by air pressurization seepage technique.The internal friction (damping properties) and relative dynamic modulus were tested in the temperature range of 25-400 ℃ at low frequencies and strain amplitudes by using multifunction internal friction apparatus.The microstructure of the composites was observed by means of transmission electron microscope.The results show that little micro pores were found on the interface of the composites,and the bonding between the particles and the matrix was weak.With the increase of the graphite particulate volume fraction the damping properties of the composites with same graphite particles grain size increased.With the increase of the graphite particulate grain size the damping properties of the composites with same graphite particulate volume fraction increased.Compared with the damping properties of the commercially pure aluminum,the damping properties of the composites increased 2-3 times.The main damping mechanisms for the composites were the interface damping and dislocation damping.