Mesenchymal stem cells （MSCs） are progenitors with strong proliferation and multi-differentiation potential. According to different sources，MSCs can be divided into bone marrow，placental，umbilical and fat mesenchymal stem cells. MSCs are promising candidates for cell-based therapies and for the promotion of tissue repair. However，the promotion effect of MSCs on tumor cells in some cases cannot be ignored. This paper reviews the recent literature on the bidirectional regulation of MSCs in tumor cells，and explores the mechanism and law of inhibiting or promoting the proliferation，migration and invasion of tumor cells，so as to provide reference for scientific and reasonable clinical trials of MSCs.