Composites of graphene nanoplatelets (GNPs) and 8030 aluminum alloy powder were prepared using powder modification + semisolid extrusion processes. The density, electrical conductivity, mechanical properties and microstructure of the specimens were investigated. The results show that the composites with 0.5 wt% GNPs achieved an enhancement in yield strength (37.5%) and ultimate tensile strength (62.9%), while its elongation and electrical conductivity were comparable, as compared with the 8030 aluminum alloy without GNPs prepared by the same process. Furthermore, the related strengthening mechanism of the composites with GNPs directional distribution was discussed.