The immunosuppressive tumor microenvironment is one of the key factors to promote tumor progression. Myeloid-derived suppressor cells(MDSCs)are the main immunosuppressive cells involved in the formation of tumor immune microenvironment,representing the heterogeneous group of immature bone marrow cells,proliferating,activating and exerting significant immunosuppressive activity under the pathological conditions. MDSCs are also the potential therapeutic targets for tumor immunotherapy. This article summarizes the origin,phenotype and biological characteristics of MDSCs,as well as its mechanisms on tumor immune escape, targeted therapeutic strategies for MDSCs and effects of Chinese medicine monomer on MDSCs, so as to provide references for tumor immunotherapy.