The stir-casting method was utilized in this paper to synthesize 6063Al/Al2O3·SiO2 reinforced composites consisting of 6063Al alloy as matrix and Al2O3·SiO2 particles as additive with content of 5%, 10%, 15%, 20% (volume fraction) respectively. Al2O3·SiO2 particles were obtained from fly ash particles of Steam Power Plant and were pretreated. The shape of these fly ash particles was spheroidal and ellipsoidal. The damping behavior of 6063Al/Al2O3·SiO2 particle reinforced composites was studied by measuring the composite’s internal friction values on a Multifunctional Damping Measurement Apparatus. Under the condition of this series of experiments, 6063Al/Al2O3·SiO2 particle reinforced composites had a higher internal friction values than that of 6063Al matrix and also showed the dependency of internal friction on Al2O3·SiO2 particles volume fraction, particles dimension, vibration frequency and temperature. There was an increased trend for internal friction values with increasing the volume fraction of Al2O3·SiO2 particles and decreasing particles dimension of Al2O3·SiO2 at the same frequency and the different temperature. It has been found that in the lower frequency, the higher internal friction value was obtained. The internal friction of the composites increased with increasing temperature. In the case of lower frequency, two damping peak were observed. A low-temperature damping peak appeared at a temperature near 245°C which a high-temperature damping peak appeared near 450°C. Based on the experimental results, the damping mechanism of 6063Al/Al2O3·SiO2 particle reinforced composites was preliminary discussed. It may be concluded that the damping mechanisms associated with 6063Al/Al2O3·SiO2 reinforced composites include mainly intrinsic damping, dislocation damping and interface damping. However, only the interface damping mechanism is dominant at high temperature.