Graphene-reinforced 7055 aluminum alloy composites with different contents of graphene were prepared by spark plasma sintering(SPS). The structure and mechanical properties of the composites were investigated. Testing results show that the hardness, compressive strength, and yield strength of the composites are improved with the addition of 1wt% graphene. A clean, strong interface is formed between the metal matrix and graphene via metallurgical bonding on atomic scale. Harmful aluminum carbide(Al_4C_3) is not formed during SPS processing. Further addition of graphene(above 1wt%) results in the deterioration in mechanical properties of the composites. The agglomeration of graphene plates is exacerbated with increasing graphene content, which is the main reason for this deterioration. Graphene-reinforced 7055 aluminum alloy composites with different contents of graphene were prepared by spark plasma sintering (SPS). The structure and mechanical properties of the composites were investigated. Testing results show that the hardness, compressive strength, and yield strength of the composites are Improved with the addition of 1 wt% graphene. A clean, strong interface is formed between the metal matrix and graphene via metallurgical bonding on atomic scale. Harmful aluminum carbide (Al_4C_3) is not formed during SPS processing. Further addition of graphene (above 1 wt% ) results in the deterioration in mechanical properties of the composites. The agglomeration of graphene plates is exacerbated with increasing graphene content, which is the main reason for this deterioration.