The fluorescence energy transfer（FET） between Fluorescein and Phenosafranine systems as a fluorescent probe and its application in the determination of Cu2+ were reported.The linear range was 0.5～20.0 μg·mL-1.The detection limit was 0.7ng·mL-1 and the relative standard deviation（RSD） was 3.8% for the determination of 8.0μg·mL-1 Cu2+（n=10）.The fluorescent probe was applied to the determination of Cu2+ in mixed sample with satisfactory result.
