The effect of aging treatment on the damping capacity of the high strength damping aluminum alloy prepared by RS/PM process was investigated. The damping properties of the alloy were examined with dynamic mechanic thermal analyzer (DMTA). The damping capacity, as well as the dynamic Young’s modulus was measured at different temperatures and different loading frequencies. The analysis of microstructure characteristics was performed using transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the damping capacity of the alloy did not change significantly after aging treatment, but changed remarkably with the variation of measurement temperature and loading frequency. Grain boundaries in the alloy became clear and sharp with aging treatment proceeded and contributed to the total damping capacity.