Provided are a graphene-based compound, a preparation method thereof, a single-phase composition for preparing a graphene-based compound, and a graphene quantum dot. Specifically, provided are a graphene-based compound prepared from a single-phase composition for preparing a graphene-based compound including hydrocarbyl amine, a hydroxyl group-containing carbon source, and an acid, a preparation method thereof, a single-phase composition for preparing a graphene-based compound, and a graphene quantum dot.