Abstract: The present disclosure provides a method for promoting the growth of parietal decidual basalis-mesenchymal stem cells (PDB-MSCs), which comprises promoting the growth of parietal decidual basalis-mesenchymal stem cells (PDB-MSCs) via a human umbilical cord-mesenchymal stem cell (UC-MSC)-derived exosome. In the present disclosure, after the PDB-MSCs are co-cultivated with the human UC-MSC-derived exosome, the PDB-MSCs show strong cell proliferation ability, prominent cell shape, and desirable cell viability. That is, the human UC-MSC-derived exosome of the present disclosure can improve a quality of PDB-MSCs and effectively improve the ability of PDB-MSCs to secrete vascular endothelial growth factor (VEGF) and stem cell factor (SCF), so as to solve the problem that PDB-MSCs show decreased proliferation ability and poor cell viability after multiple passages, which effectively facilitates the large-scale cultivation and clinical practice of PDB-MSCs.