Abstract: A graphene composite coating layer for being coated on the surface of the target object comprises a curable mixed resin more than 97 wt % and a plurality of surface modified nano graphene sheets. The curable mixed resin comprises a curable resin and a curing agent. The curable resin is 10-50 wt % of the curable mixed resin, and the curing agent is 0˜10 wt % of the curable mixed resin. The surface modified graphene sheets with less than 3 wt % of the graphene composite coating layer are evenly spread in the curable mixed resin. The surface of the surface modified nano graphene sheet has some specific functional groups to form effective bonding with the curable mixed resin, thereby improving the compatibility of the surface modified nano graphene sheets and the curable mixed resin, increasing the junction strength, and enhancing the functions like anti-oxidation, acid/base resistance and mechanical strength.