In this paper,based on the photoinduced electron transfer(PET) mechanism,a specific cysteine fluorescence probe was successfully synthesized.The probe molecules reacted with Cys to make nucleophilic substitution because of its strong nucleophilicity,resulting in the departure of acryl and inhibiting the PET process of probe molecular system.When adding a variety of test analytes into the probe solution,only Hcy and GSH,which have a similar structure with Cys,led to a weak fluorescence variation of probe solution,other amino acids could make no change of the fluorescence intensity.With good selectivity and sensitivity to Cys,the probe could be used to detect Cys under physiological conditions,and distinguish Hcy and GSH.Meanwhile,the probe successfully realized the fluorescence imaging of Cys in cells,and established a specific Cys recognition analysis method for practical applications in biology and medicine.