The invention discloses a fluorescent probe for detecting biological thiols. The molecular structural formula of the fluorescent probe is shown in the description. The fluorescent probe has weak fluorescence, and after the fluorescent probe responds to biological thiols, a liquor emits red light. The probe molecule not only can be applied to a pure water system for detecting biological thiols, butalso can rapidly identify and quantitatively detect biological thiols in cells. The fluorescent probe has important application value in the field of biochemistry.