We　report　a　room-temperature　strategy　for　the　synthesis　of　single-crystalline　fluorescent　graphene　quantum　dots　(GQDs)　via　electron-beam　irradiation.　The　precursor　contained　high-activity　nitro　groups　is　easy　to　fusion　GQDs　with　the　method.　Under　optimized　conditions　(0.02　g　1,3,6-trinitropyrene,　radiation　dose　of　400　kGy　and　10　ml　0.5　mol/L　hydrazine　hydrate),　the　GQDs　exhibit　highly　efficient　fluorescence　at　475　nm　with　a　quantum　yield　of　32%.　The　PL　maximum　is　well　corresponded　with　the　excitation　wavelength.　Moreover,　the　single-exponential　fluorescence　lifetime　(4.86　ns)　exhibited　the　intrinsic　PL　characteristic.　The　pH　stability　in　neutral　and　alkaline　solution,　solid　solubility　and　storage　time　stability　of　GQDs　are　satisfactory.　Their　application　as　a　safety　fluorescent　probe　for　cell　imaging　is　demonstrated.　(C)　2016　Published　by　Elsevier　B.V.