Reducing glutathione (GSH) is used as a stabilizer to synthesize gold nanoclusters (GSH-AuNCs) with good stability and water solubility. The specific static quenching effect of Cu ²⁺ on GSH-AuNCs fluorescence in aqueous solution is used to establish a rapid and highly sensitive detection method for Cu ²⁺. GSH-AuNCs emits strong fluorescence at 602 nm under the excitation light of 396 nm wavelength. When Cu ²⁺ exists in the GSH-AuNCs system, the fluorescence signal is quenched to a certain extent, and the greater the concentration of Cu ²⁺, the more significant the effect, the linear relationship between the fluorescence emission intensity of GSH-AuNCs and the concentration of Cu ²⁺ is established based on this, and the quantitative detection of Cu ²⁺ is realized. Under optimized conditions, the fluorescence emission signal of GSH-AuNCs showes a good linear relationship with Cu ²⁺concentration between 16.7 and 5000 nmol·L ^-1, and the detection limit is 7.4 nmol·L ^-1. At the same time, the recovery rate of the actual water sample is detected, the recovery rate is between 92.9% and 107.9%.