The work aims to improve the dispersibility of graphene in the organic coating and give it a certain functionality to prepare a water-based epoxy composite coating with simple method, environmental friendliness and low cost. Graphene oxide was selected as raw material and EDC was chosen as condensing agent. At ambient temperature, a natural corrosion inhibitor was grafted on the surface of graphene oxide through amidation reaction. Tryptophan functionalized graphene was prepared by hydrazine reduction and then successfully dispersed into waterborne epoxy resin to obtain the tryptophan functionalized gra-phene/epoxy coating. FTIR, Raman, SEM and TEM were employed to analyze the laminate structure and morphology of func-tionalized graphene. The corrosion resistance of as-prepared coating in 3.5%NaCl solution was evaluated by electrochemical workstation. Tryptophan was successfully grafted onto the surface of graphene oxide, and the functionalized graphene exhibited excellent dispersibility in absolute ethanol and waterborne epoxy resin. In terms of protective performance, the functionalized graphene-based composite coating displayed the highest impedance modulus (107 Ω?cm2) and charge transfer resistance after 40 days of immersion compared to the blank and unmodified graphene-based composite coating. Meanwhile, the surface of metal substrate exhibited the slightest corrosion among all coatings after being covered by the functionalized graphene composite coating. Thus, the addition of functional graphene can significantly improve the corrosion resistance of waterborne epoxy coating.