An economical idea was developed to synthesize fluorescent carbon quantum dots(CQDs) directly from the refluxing extraction of orange pericarp via a hydrothermal technique. Hydrothermal temperatures and times were adjusted to control the particle sizes and the quantum yields of the obtained CQDs. The as-prepared carbon quantum dots showed narrow particle size distribution, good water solubility, and acceptable fluorescence lifetimes. Due to their high stability, these obtained carbon quantum dots have great application potential in nano-biotechnology. Furthermore, carbon spheres with uniform morphology and size can be easily obtained as the reaction byproducts of this green synthesis process. An economical idea was developed to synthesize fluorescent carbon quantum dots (CQDs) directly from the refluxing extraction of orange pericarp via a hydrothermal technique. Hydrothermal temperatures and times were adjusted to control the particle sizes and the quantum yields of the obtained CQDs. The as- Due to their high stability, these obtained carbon quantum dots have great application potential in nano-biotechnology. Furthermore, carbon spheres with uniform morphology and size can be easily obtained as the reaction byproducts of this green synthesis process.