In order to further improve the barrier effect of epoxy micaceous iron oxide（MIO） intermediate coatings，and solve the problem of its insufficient long-term protection in the high humidity and summer high heat of the hydraulic environment. In this paper，the effects of the thin-layer graphene addition to epoxy MIO coatings on the adhesion，impact，salt spray and electrochemical properties were investigated. The results showed that the synergistic lamellar structure of nanoscale graphene and micrometer-scale muscovite iron provided a mechanism for micro-nano shielding property. After adding a small amount of graphene，the properties of the coating were significantly improved，especially the water permeability resistance，impact resistance and the adhesion of the coating after soaking in water，so that the graphene-modified epoxy MIO intermediate coatings could provide more effective and durable corrosion protection forsteel structures in high-humidity and high-heat hydraulic application environments.