In this paper,nitrogen-doped graphene quantum dots(N-GQDs) were prepared by one-step hydrothermal synthesis.Cu2+ ions were combined with the specific functional groups on surfaces of the quantum dots to form N-GQDs-Cu2+ complexes,which could quench fluorescence effectively.Furthermore,when 2-mercaptobenzothiazole(MBT) was added,Cu2+ were dissociated from the surface of the quantum dots due to the strong force of MBT and Cu2+,and the fluorescence from the quantum dots was recovered.Thus,a highly sensitive fluorescence sensor based on Cu2+ modified N-GQDsnitrogen-doped graphene quantum dots was constructed for the detection of MBT.Under the optimal experimental conditions,there was a good linear relationship between MBT and fluorescence recovery intensity in the concentration range of 0.4-40.0 μmol/L,and the limit of detection was 0.1 μmol/L.The method could be applied in the detection of MBT in real water samples with spiked recoveries of 95.0%-101%.