The invention belongs to the technical field of biological medicine, and designs a multifunctional graphene gene vector, a gene transfection reagent based on the gene vector and a preparation method thereof. The multifunctional graphene comprises the following three parts of graphene, cationic polymer, and an active reagent, wherein the active reagent comprises one or more than one of a surfactant, or cell-penetrating peptide, or nuclear localization signal peptide; the cationic polymer and the active reagent are connected to the graphene. According to the invention, through multi-functionalization, the stability, dispersibility, biocompatibility of the gene vector in the gene transfection process are improved; the toxicity is reduced; and a plurality of gene transfection promotion mechanisms are adopted to improve transfection efficiency. Gene transfection experiment results show that high transfection efficiency and low toxicity are realized in a plurality of cell strains. The main purpose of the invention is gene transfection, and is applicable to cytobiological research, gene product production, and gene therapy.