The invention provides a preparation method of a graphene-metallic oxide composite coating. The preparation method comprises the following steps: firstly, preparing a coating material which comprisesat least 5 wt% to 10 wt% of n-tetrabutyl titanate, 0.05 wt% to 1 wt% of a graphene derivative, 0.05 wt% to 1wt% of a surfactant, water and ethyl alcohol; then preparing the coating by applying the coating material to a surface of a base material with at least one methods of spraying, dip-coating and brushing; and further drying the coating on the surface of the base material at a temperature of 100-400 DEG C to form a film. The graphene-metallic oxide composite coating provided by the invention is excellent in corrosion resistance, strong in substrate bonding force and controllable in process,and can be applied to surface coating protection of marine equipment, new energy vehicles, building alloy materials and the like.