Abstract：Objective：To observe the effect of modified Sijunzi tang on immune function and quality of life in patients with advanced rectal cancer. Methods：A total of 120 cases of patients with advanced rectal cancer were selected and divided into the observation group and the control group according to the random number table method， 60 cases in each group. The control group was given chemotherapy based on FOLFOX6 regimen，and the observation group was additionally treated with modified Sijunzi tang based on the treatment of the control group. The short- term clinical effect in the two groups was compared；the changes of immune function and quality of life were evaluated. Results：The total effective rate of short-term clinical effect was 65.00% in the observation group，higher than that of 30.00% in the control group，the difference being significant(P＜0.05). Before treatment， there was no significant difference being found in the comparison of the levels of immunoglobulin A(IgA)，IgM and IgG between the two group(P＞0.05). After treatment，the levels of IgA，IgM and IgG in the two groups were increased when compared with those before treatment(P＜0.05)， and the levels in the observation group were higher than those in the control group(P＜0.05). Before treatment， there was no significant difference being found in the comparison of CD4+，CD8+ and CD4+/CD8+ between the two groups(P＞0.05). After treatment，the indexes of CD4+，CD8+ and CD4+/CD8+ in the two groups were increased when compared with those before treatment(P＜0.05)，and the above indexes in the observation group were all higher than those in the control group(P＜0.05). Before treatment，there was no significant difference being found in the comparison of the scores of quality of life between the two groups(P＞0.05). After treatment，the scores of quality of life in the two groups were increased when compared with those before treatment (P＜0.05)， and the score in the observation group was higher than that in the control group(P＜0.05). Conclusion： The application of modified Sijunzi tang for patients with advanced rectal cancer can improve the short- term clinical effect，the immune function，and the quality of life.