Objective:To observe the effects of Yiqi Fusheng Recipe (YQFS) combined with chemotherapy on tumor infiltrating lymphocytes in the tumor microenvironment, and to explore the mechanism of action of YQFS combined with chemotherapy on tumor growth in tumor-bearing mice with gastric cancer. MethodsThe MFC gastric cancer cells were inoculated to mice under the armpit, and the tumor bearing model of mice was established. The mice were divided into five groups, namely blank control group, model group, 5-FU + low-dose YQFS group, 5-FU + high-dose YQFS group and 5-FU group. The blank control group was not treated, the model group was given 0.9% NaCl solution by gastric gavage, the 5-FU + low-dose and 5-FU+ high-dose YQFS groups were given 5-FU intraperitoneal injection for 7 days and different doses of YQFS by gastric gavage for 21 days, and the 5-FU group was given 5-FU intraperitoneal injection for 7 days. Materials were taken after 21 days, the tumor tissue and spleen of tumor-bearing mice with MFC gastric cancer were weighed to calculate the tumor inhibition rate and the spleen index. The levels and proportions of CD4 and CD8 subsets in tumor infiltrating lymphocytes were detected by flow cytometry. The changes in expression of IFN-γ, TNF-α, IL-10 and IL-6 in peripheral blood were detected by ELISA. Pathological changes of gastric mucosa in mice were observed by HE staining of tissue sections.  Results:The inhibition rate of YQFS combined with chemotherapy was 54.46% in tumor-bearing mice with gastric cancer, significantly different from that of chemotherapy alone. YQFS combined with chemotherapy could change the shape of gastric mucosa and reduce spleen index, which decreased with increase in YQFS concentration in a dose-dependent manner (P,<,0.05). Compared with the model group, YQFS combined with chemotherapy could increase the ratio of CD4,+,/CD8,+, in tumor infiltrating lymphocytes and the proportion of CD4,+,; it could also increase the expression of INF-γ in peripheral blood of tumor-bearing mice with gastric cancer, and reduce the expression of IL-10, IL-6 and TNF-α, showing dose-dependent changes with the concentration of YQFS.  Conclusion:The anti-tumor effects of YQFS combined with chemotherapy may be related to increase of the CD4,+,/CD8,+, ratio in tumor infiltrating lymphocytes, decrease in spleen index, up-regulation of INF-γ and down-regulation of IL-10, IL-6 and TNF-α in peripheral blood, recovery of tumor immunization homeostasis and improvement of immunity in tumor-bearing mice with gastric cancer.