Abstract: The endoplasmic reticulum (ER) is an important organelle in eukaryotic cells involved in a variety of physiological processes．Endoplasmic reticulum stress often leads to the generation of biologically active molecules, to regulate physiological activities in different cell types, with implications for cancer and non-malignant lesions．Bioactive species such as reactive oxygen, nitrogen and sulfur species tend to have high redox and biological activities, and are involved in pathological processes．Fluorescent probes for these biologically active species often offer excellent optical properties, outstanding positioning, and are good for multi-functional real-time in situ monitoring．Monitoring of active species in the ER by fluorescence imaging has great potential in metabolic diseases and cancer．Fluorescent probes targeted to ER developed in recent years are summarized in this review．