Graphene nanoplatelets (GNPs) reinforced A380 composites (GNPs/A380 composites) were prepared by ultrasonic vibration casting method. The microstructure, aging behavior and mechanical properties of the composites were investigated. It was found that the peak aging time of GNPs/A380 composites could be decreased by GNPs. The GNPs-Al interface could serve as a more stable nucleation site for the precipitated phases. With bridging GNPs, the coordinated deformation of the matrix is increased and larger dimples appear on the fracture surface of GNPs/A380 composites. The yield strength of the GNPs/A380 composites increased by 28.1% compared with that of the A380 alloy due to the fine grain strengthening, load transfer and precipitation strengthening mechanisms.