The invention provides a method for preparing flake graphene-aluminum mixed powder with silicone oil serving as a grinding aid and a repairing agent and relates to the method for preparing the graphene-aluminum mixed powder. The problems that in the process that the flake aluminum powder is prepared through a ball-milling method, the defect content of graphene is high, agglomeration of aluminum powder particles occurs, and the prepared flake aluminum powder is prone to be oxidized are solved. The preparation method comprises the steps that the graphene, the silicone oil and the aluminum powderare weighed to serve as raw materials; the raw materials are subjected to ball-milling again after being subjected to ball-milling and premixing, an obtained powder body is subjected to heat preservation in a vacuum or atmospheric constant-temperature furnace, finally sieving and separating are performed, and the graphene-aluminum mixed powder is obtained. The silicone oil is selected as the grinding aid, the flake aluminum powder is separated from the surface of a ball-milling medium beneficially, agglomeration is avoided, cold welding and oxidation of the aluminum powder are avoided, ball-milling time can be remarkably shortened, ball-milling efficiency is improved, dispersing of the graphene in the aluminum powder is facilitated, the silicone oil is discomposed to generate free Si atoms to repair and remedy the defect structure, the stability of the graphene is improved, and good Al-Si-C interface combination is formed. The method is suitable for preparing the flake graphene-aluminum mixed powder.