Abstract: Different contents of graphene aluminum matrix composites (mass fraction of 0, 0.2%, 0.5%, 0.8%, 1.0%) were prepared by ball milling and discharge plasma sintering technology. Scanning electron microscope, energy dispersion spectrometer, X ray diffraction, Raman spectrometer, and X ray photoelectron spectroscopy were used to characterize the microstructure, defectsand chemical valence of surface elements of the sintered samples. And the influence of graphene content on the thermal conductivity and microhardness of aluminum matrix composites were studied. The results show that adding graphene can improve the microhardness and thermal conductivity of aluminum matrix composites, and the increase of thermal conductivity is more significant. For the composites with 0.2% mass fraction of graphene, both the microhardness and thermal conductivityreach the maximum values, compared with aluminum matrix materials, the microhardness and thermal conductivity of composite materials was increased by 24% and 204%, respectively. However, when the mass fraction of graphene continues to increase to 0.5%, 0.8% and 1.0%, the microhardness and thermal conductivity of the composites do not increase significantly.The main reason is that with the increase of graphene content,the agglomeration between graphene sheets becomes more serious, which leads to the failure of further improvement of microhardness and thermal conductivity of aluminum matrix composites.