Stem cells have the ability to regenerate and differentiate,and stem cell transplantation has been increasingly used in the treatment of diseases.In the experimental study of stem cell transplantation,stem cells need to be labeled in order to observe and trace their distribution and proliferation in the host.There are two main classes of cell labeling methods for molecular imaging:the direct and indirect labeling methods.The direct labeling is the direct introduction of labeling reagents into stem cells,and the indirect labeling is the integration of reporter genes into cells,and then detection of the gene expression products.In this paper,the advantages and disadvantages of stem cell monitoring technology and its research progress were reviewed.