MDSCs are a group of heterogeneous cells which derived from immature bone marrow cells. They are the precursor cells of dendritic cell, macrophage and granulocyte. In tumor carrier’s body, they can strongly suppress the anti-tumor immune response. Other researchers found that if we cleared MDSCs, tumor will shrink. So it’s important to find a drug that could kill MDSCs. This research studied the inhibitory effect and molecular mechanism of asparagus polysacchride(AP) on MDSCs. Found that AP can selectively induces MDSCs to apoptosis. Apoptosis-related gene such as P53 participated in the process. TLR4 is possible the receptor of AP on MDSCs. This study proved that AP could assisted in anti-tumor therapy based on the study of mechanism and this provides basis for the development of new drug.