Mesenchymal stem cells (MSC) are capable of immunosuppression and differentiating into multiple cell lineages. MSC, which are accessed easily and less side-effects, have been a source of seed cells in tissue-engineering and cell-therapy. However, the application of MSC are limited by their differentiation of instability and easy aging. MicroRNA-155 (miR-155) is one of microRNA, which has powerful regulatory potential in a wide variety of immune cells through degrading specific mRNA after transcription and inhibiting translation of the target genes. Following the research of miR-155 deeply, it has an indispensable role in the proliferation, differentiation and immunoregulation of MSC. This review discusses the current understandings for the role of miR-155 in MSC.