Mass-encoded probe is a probing tool that specifically identifies target molecules and thus outputs their characteristic ion signals with mass tags.It plays an important role in multiplex assay of disease markers, drug target screening and other biomedical applications.Based on various mass spectrometric methods, researchers have developed an array of mass tag-encoded probes with different structures and functions, providing powerful technical tools for multiplex detection of biomolecules in physiological environments and for mass spectrometry imaging of tissue samples.This review introduces the latest research progress of mass tag-encoded probes in multiplex mass spectrometric detection from three aspects, i.e. structural composition of the probes, mass spectrometric methods and their application in biochemical analysis, with a prospect of the future development of mass tag-encoded probes.