To prepare carbon-based fluorescence materials such as graphene quantum dots (GQDs), new and effective methods to convert one-dimensional (1D) or two-dimensional (2D) carbon materials to 0D GQDs are needed. Here, we report a novel acid-free and oxone oxidant-assisted solvothermal synthesis of GQDs using various natural carbon resources including graphite (G), multiwall carbon nanotube (M), carbon fiber (CF), and charcoal (C). This acid-free method, not requiring the neutralization process of strong acids, exhibits a simple and eco-friendly purification process and also represents a recycling production process, together with mass production and high yield. The newly synthesized GQDs exhibited a strong blue photoluminescence (PL) under 365 nm UV light illumination. The PL emission peaks of all the recycled GQDs were not changed.