Graphene quantum dots (GQDs)are two-dimensional carbon nano-material with excellent physicochemical properties,including biocompatibility,high photoluminescence,water-solubility,hypotoxicity and so on.Owing to big π-conjugated structure and oxygen-containing functional groups,GQDs have the ability to absorb various chemical drugs via π-π stacking and electrostatic interaction.On the other hand,owning to photoluminescence,GQDs also have potential to serve as fluorescence probe for bioimaging,especially for optical diagnostics.In addition,GQDs have the ability to generate reactive oxygen species (ROS)including singlet oxygen upon photoexcitation.Therefore,GQDs are likely to be used for photodynamic therapy.This article aims to review the frontier researches about GQDs in the field of fluorescence probe,photodynamic therapy and anti-tumor drug delivery system.