Abstract: Objective To analyze the effect of Ginseng polysaccharide on the chemotherapy efficacy and the levels of myeloid-derived suppressor cells (MDSCs), regulatory T cells (Treg) and immune factors in advanced non-small cell lung cancer (NSCLC). Methods Sixty-three patients with advanced NSCLC in Zhejiang Provincial People's Hospital between June 2014 and December 2015 were selected as the subjects, and randomly divided into the Ginseng polysaccharide group and the control group. The two groups were treated with GP or DP chemotherapy, and Ginseng Polysacchride Injection was added to the Ginseng polysaccharide group. The clinical efficacy, quality of life and adverse reaction of the patients in the two groups were compared. The MDSCs, Treg cell and the correlation between the two groups were compared. and the arginase and various cytokines (VEGF, TGF-β, IL-10, IFN-γ, TNF-α) in the two groups were compared. Results The rate of disease control and quality of life in the Ginseng polysaccharide group were both significantly higher than that in the control group (all P<0.05). leukocyte reduction, nausea and vomiting in Ginseng polysaccharide group were significantly lower than those in the control group (all P<0.05). There was no significant difference in the percentage of MDSCs and Treg cells between the 2 groups before treatment (all P>0.05). The percentages of MDSCs and Treg cells in the 2 groups were significantly higher than those in the control group after treatment (all P<0.05). Treg cells were positively correlated with MDSCs (P<0.05). After the treatment, compared with the control group, the arginine, VEGF, TGF-β, and IL-10 decreased significantly (all P<0.05), and IFN-γ, TNF-α increased significantly in the Ginseng polysaccharides group (all P<0.05). Conclusion By affecting the MDSCs, Treg and immune factors, Ginseng polysaccharide can improve the immune function, the efficacy and quality of life, and reduce the adverse reactions of advanced NSCLC patients receiving chemotherapy.