The invention discloses a preparation method of graphene/epoxy flake anticorrosive coating. The preparation method comprises the following steps: 1) with a large-sheet graphene oxide aqueous solutionas a raw material, adding a reducing agent, and carrying out self-assembly to obtain graphene microgel; 2) modifying the graphene microgel by a modifier; and 3) mixing the modified graphene microgel,epoxy resin, a curing agent and a defoaming agent, and carrying out a pouring process to obtain the graphene/epoxy flake anticorrosive coating with high corrosion resistance. The graphene flake anticorrosive coating is prepared by adopting the methods of graphene microgel, modifying agent modification and pouring molding. The process is simple, low in cost and suitable for large-scale industrial production.