To analyze the distribution characteristics and correlation of intestinal flora and TB lymphocyte subpopulations in Chinese medicine beneficiaries of metastatic colorectal cancer(mCRC). Methods:From March 2018 to March 2019, a total of 40 patients with mCRC admitted to the Oncology Department or Ward of Xiyuan Hospital of the Chinese Academy of Chinese Medical Sciences were selected as the research objects. A randomized double-blind, placebo-controlled clinical research method was used and the patients were randomly divided into a treatment groups and a placebo group. The treatment group was given conventional Chinese medicine treatment plus Quxie Capsules, and the control group was given placebo capsules on the basis of the same treatment as the treatment group. Stool samples and peripheral blood samples of patients at baseline were collected and tested. According to the survival outcome of the three-year follow-up of the enrolled patients and the criteria for determining the dominant group of Chinese medicine treatment of mCRC, the patients were divided into a dominant group and a non-dominant group of traditional Chinese medicine treatment. The difference and correlation of intestinal flora and TB lymphocyte subgroups between the 2 groups were analyzed.Results:The Alpha diversity analysis of the intestinal flora showed that the Chinese medicine in the treatment of non-beneficiaries populations had a higher SOBS index than the Chinese medicine beneficiaries populations group and there was a significant statistical difference (115.17±19.25 vs. 81.96±36.79, P=0.005). Chinese medicine beneficiaries populations group had a higher proportion of Bacteroides (30.6% vs. 23.9%, P=0.33) and Prevotella (5.7% vs.3.9%, P=0.69); the analysis of TB lymphocyte subsets found that the Chinese medicine beneficiaries populations group had a higher absolute value of double-negative T cells (89.6±82.0 vs. 37.1±16.5, P=0.01) and non-HLA dependent group than the other group (83.0±43.6 vs.28.4±18.3)，P=0.01); the absolute value of HLA-dependent cytotoxic T cells was significantly negatively correlated with Anaerostipes (P=0.04). Conclusion:there are significant differences in the distribution of intestinal flora and the characteristics of TB lymphocyte subgroups between the dominant and non-advantaged groups of Chinese medicine treatment of mCRC, which provide a necessary scientific basis for further explaining the characteristics of the dominant group of traditional Chinese medicine and the mechanism of efficacy.