Graphene　has　excellent　application　prospects　in　anti-corrosion　coatings　because　of　its　perfect　impermeability.　Unfortunately,　graphene　sheets　rich　in　surface　defects　lead　to　a　significant　reduction　in　impermeability,　and　also　tend　to　spontaneously　aggregate　and　randomly　arrange　in　the　resin　matrix　to　form　conductive　network,　which　exacerbates　electrochemical　corrosion　reactions.　Herein,　a　green,　one-step　method　for　preparing　low-defect　and　few-layer　modified　graphene　was　proposed.　Graphene　was　prepared　and　modified　in　one　step　from　graphite　by　using　calcein　(CA)　under　microfluidization　process　to　obtain　CA　noncovalent　modified　graphene　(CAG)　with　2–5　layers　of　sheets.　CAG/epoxy　(EP)　coatings　with　high　orientation　were　prepared　by　spinning　and　curing　simultaneously.　The　coatings　show　excellent　long-term　anti-corrosion　performance.　After　immersion　for　55　days　in　3.5　wt%　NaCl　solution,　the　impedance　modulus　of　CAG0.5%/EP　coating　was　about　three　orders　of　magnitude　higher　than　that　of　EP　coating.　It　is　worth　noting　that　when　the　CAG　content　increased　to　1　%,　the　impedance　value　remained　above　1.8　×　1011　Ω　cm2.　The　excellent　anti-corrosive　properties　of　the　composite　coating　can　be　attributed　to　the　extremely　high　orientation　of　graphene,　which　prevents　the　formation　of　conductive　pathways　and　maximizes　the　barrier　effect　of　graphene.　In　parallel,　the　modified　graphene　reduces　the　agglomeration　between　the　graphene　sheet　and　imparts　excellent　interfacial　bonding　with　the　epoxy,　thus　avoiding　the　formation　of　micro-cracks　in　the　coating.　©　2023