Objective To observe the effects of Modified Jianpi Jiedu Formula（健脾解毒方） on intestinal flora and immune function in advanced colorectal cancer patients with spleen qi deficiency syndrome treated with chemotherapy. Methods A total of 56 advanced colorectal cancer patients with spleen qi deficiency syndrome were randomly divided into a control group and a observation group with 28 patients in each group. The control group received XELOX and FOLFOX4 chemotherapy. On the basis of the control group

the observation group was given Modified Jianpi Jiedu Formula（健脾解毒方） orally

1 dose daily. After 8 weeks

the Karnorfsky scores（KPS）

syndrome scores in traditional Chinese medicine

immune indicators

intestinal flora

and fecal secretory immunoglobulin A（sIgA） levels of both groups of patients were compared after treatment

and the clinical efficacy was determined. Results The total effective rate of clinical effects in the observation group was 60.71%

and that in the control group was 21.43%. The clinical effects in the observation group was superior to that in the control group（P

<

0.01）. After treatment

the KPS

CD3

+

CD4

+

CD4

+

/CD8

+

natural killer cells

sIgA levels

and the number of lactobacillus and bifidobacteria were significantly increased in the observation group

and were higher than those in the control group（P

<

0.05 or P

<

0.01）. The syndrome scores

CD8

+

level

the number of intestinal E. coli and enterococci of the observation group were also lower than those before treatment

and were lower than those of the control group（P

<

0.05 or P

<

0.01）. Conclusion Modified Jianpi Jiedu Formula（健脾解毒方） has the effects of regulating intestinal flora imbalance and protecting the intestinal barrier. This may be the important causes of Modified Jianpi Jiedu Formula（健脾解毒方） improving the symptoms of spleen deficiency in patients with colorectal cancer chemotherapy

reducing adverse reactions to chemotherapy

improving quality of life

and enhancing nonspecific immune function.