Cadmium is a toxic heavy metal, which is both an environmental pollutant, and a threat to human health. A fluorescent probe was developed to detect Cd 2+ selectively, sensitively, and quickly. This study reports the successful development of a polypeptide fluorescent probe TPE-HC (TPE-His-Pro-Gly-Cys) which selectively detects Cd 2+ by Aggregation-Induced Emission effect. After fluorescence excitation, Cd 2+ can be effectively detected based on the change of fluorescence intensity. The detection limit of Cd 2+ in buffer solution was determined to be 151 nM (R 2 = 0.9933). This probe exhibits high sensitivity, high cell permeabilit y, and low biological toxicity, and can perform live cell imaging under biological conditions. This study indicates that TPE-HC can detect Cd 2+ in biological environments.