In recent years, in fields of an eco-friendly automobile, an advanced industrial machine, and a precision electronic device, controlling of vibration damping behavior of the sintered materials is required. In this paper, vibration damping analysis of Cu-Sn/Carbon fiber sintered composite materials was performed by frequency response function of FFT analyzer, and the results was compared with Cu-Sn/Graphite sintered composite materials.Cu, Sn elemental powders and Carbon fiber were used as initial substances. The powders and the fiber were mixed and pressed into a plate shaped compact with 200 MPa. Using a vacuum furnace, the green compact was sintered at 825-1075°C for 1 hour. By changing the mixing ratio and the sintering temperature, some kinds of the composite material plates were prepared. For the composite material obtained, microstructure, Vickers hardness, compression strength and vibration behavior were investigated.The composite materials were consisted from the crystal grain of 17-70 μm, and the mixed Carbon fiber were dispersed in the microstructure. Twin crystal was also found in the composite materials obtained. Vibration damping behavior of the Cu-Sn/Carbon fiber sintered composite material was affected by solubility element, grain boundary, dispersed Carbon fiber, and twin crystal in composite material. KEY WORDSvibration damping coefficient, FFT analyzer, lumped mass model, frequency response function, Cu-Sn/Carbon fiber sintered composite material