Abstract： Myeloid-derived suppressor cell(MDSC)is a group of regulatory cell with immunosuppressive functions.MDSC is closely related to the occurrence of inflammatory diseases.Th17 cells are a subset of CD4+T cells that play an important role in in-flammatory diseases by secreting interleukin(IL)-17,IL-22 and other cytokines.MDSC can regulate Th17 activation by expressing arginase-1,IL-1β and secreting transforming growth factor-β,thereby affecting the process of inflammatory diseases.This article re-views the mode of action of MDSC in regulating Th 17 cells and its role in inflammatory diseases such as systemic lupus erythematosus,rheumatoid arthritis and asthma.