Update information. As an important part of regenerative medicine, human umbilical cord mesenchymal stem cells show a good clinical therapeutic effect, but their use is still limited. In recent years, the use of umbilical cord mesenchymal stem cell exosomes as cell replacement therapy can effectively overcome some defects of cell therapy. However, whether there are differences among different batches of exosomes, the specific mechanism of exosomes intervention is still poorly known. In this study, LC-MS/MS was used to identify the protein composition of two generations exosomes from three different donors, and the function and possible mechanism of exosome proteomic of human umbilical cord mesenchymal stem cells was analyzed by bioinformatics. It was found that the protein composition of human umbilical cord mesenchymal stem cell exosomes was basically the same in 6 groups, and 676 core proteins were found. The biological function of core proteomic was analyzed by GO, and it was found that core proteomic was involved in 88 molecular functions, such as anion binding, nucleotide binding, receptor binding, ribonucleotide binding; 648 biological processes, such as regulation of cellular process, macromolecule metabolic process, transport; 157 cellular components. The regulation pathway of core proteomic was analyzed by KEGG, and it was found that the regulation of blood coagulation, bacterial infection, phagocytosis, vesicle circulation and so on. Umbilical cord mesenchymal stem cell exosomes were used to interfere with APP/PS1 transgenic mice to explore the mechanism of exosome regulation of synaptic vesicle cycle signal pathway in Alzheimer's disease. The results showed that the exosomes could significantly enhance the spatial memory and learning ability, exercise ability and anti-fatigue ability of Alzheimer's disease model mice. Further analysis of mouse hippocampal proteome showed that the exosome proteomic of human umbilical cord mesenchymal stem cells was enriched into 9 proteins of synaptic vesicle cycle signal pathway. Compared with control group and exosome group, the contents of AP2A1 and AP2B1 in hippocampus of model group were significantly decreased. The results of this study can provide research methods and theoretical basis for the use of human umbilical cord mesenchymal stem cell exosomes to treat diseases, and further promote its clinical application.