Abstract: In this study,the detection method of Hg²⁺ was established based on mercaptoacetic acid-modified core-shell CdTe/CdS quantum dots. The fluorescence intensity of quantum dots was characterized by fluorescence spectrometer and UV-Vis absorption spectrometer. The results showed that,when the optimum reaction conditions of Tris-HCl buffer solution with the concentration of 0.05 mol/L,pH8.0 and reaction for 15 min,Hg²⁺(10^-6~10^-4 mol/L)at different concentrations had a good fluorescence quenching effect on the quantum dots. The theoretical detection limit of Hg²⁺ by this method was 2.667 nmol/L,which was lower than the detection standard of tap water. For the fruit juice samples,the detection limit was 2.0×10^-5 mol/L. Therefore,the study provided a new insight and method for the detection of heavy metals in juice system.