Disclosed is a method of producing thin graphene nanoplatelets, and the method includes the steps of providing a carbon precursor and a filling material, using the carbon precursor as a binding agent to mix with the filling material thoroughly, producing a composite material through a forming process, performing a heat treatment of the composite material under an atmosphere and at different temperatures to improve the electrical conductivity and adjust to an appropriate binding strength, perform a carbon conversion of the composite material with a good graphite cyrstallinity to produce a layered graphite structure of a thin graphene nanoplatelet precursor, while obtaining high quality graphene by performing an electrochemical process of the thin graphene nanoplatelet precursor, so as to achieve the mass production of the high quality thin graphene nanoplateletes with a low cost.