The invention relates to a method for preparing a graphene lubricating oil additive and belongs to the technical field of lubricating oil. An oxidized graphene solution is subjected to centrifugal separation at low speed, supernatant is obtained, and the supernatant is dried at low temperature to obtain oxidized graphene powder; the oxidized graphene powder is heated in vacuum to be constantly dry, oxidized graphene powder is obtained and mixed with a dispersing agent and basic oil, after uniform mixing, the mixture is placed in a high-temperature high-pressure reaction kettle to be processed, oleophylic graphene is obtained, and the graphene lubricating oil additive is obtained by mixing the oleophylic graphene, the dispersing agent and the basic oil or mixing the oleophylic graphene with finished lubricating oil. The technology is simple and convenient, cost is reduced, all components have excellent dispersity and stability, and the problem about long-time stability of nano additives is solved. When lubricating oil where the additive is added is applied to mechanical operation, the abrasion resistance and bearing capacity of mechanical devices can be improved, and meanwhile the surfaces of the mechanical devices can be protected and highly repaired.