Abstract： Objective： To observe the clinical effect of lentinan combined with Sergio and Oxaliplatin scheme for advanced colorectal carcinoma and its effect on immune function. Methods：A total of 58 cases of patients with advanced colorectal carcinoma were divided into the control group and the observation group according to the random number table method，with 29 cases in each group. The control group was treated with SOX scheme，and the observation group was additionally treated with lentinan based on the treatment of the control group. Traditional Chinese medicine (TCM) syndrome scores， and the levels of immunoglobulin and T lymphocyte subsets were compared before and after treatment between the two groups； clinical effects and incidence of adverse reactions in the two groups were evaluated. Results： After treatment， the total effective rate was 68.97% in the control group and 82.76% in the observation group，the difference being significant (P＜0.05). After treatment，the scores of TCM syndromes including epigastric pain and fullness，poor appetite and digestion，fatigue and lack of strength，sloppy stool，pale tongue and thin coating in the two groups were decreased when compared with those before treatment (P＜ 0.05)，and the TCM syndrome scores in the observation group were lower than those in the control group (P＜0.05). After treatment，immunoglobulin (Ig) A，IgM，IgG，CD3+，CD4+ and CD4+/CD8+ in the control groups were decreased when compared with those before treatment (P＜0.05)，and CD8 + was increased (P＜0.05)；IgA，IgM，IgG，CD3+，CD4+ and CD4+/CD8+ in the observation groups were increased when compared with those before treatment (P＜0.05)， and CD8 + was decreased (P＜0.05)； the IgA， IgM， IgG，CD3+，CD4+，CD4+/CD8+ in the observation group were higher than those in the control group (P＜ 0.05)， and the CD8 + was lower than that in the control group (P＜0.05). Conclusion： Lentinan assisting SOX scheme for advanced colorectal carcinoma has a definite curative effect，and can effectively improve the immune function damage caused by chemotherapy and reduce adverse reactions，with high safety.