Abstract：Objective：To observe the clinical effect of Peiyuan Kang'ai tang for patients with postoperative chemotherapy of colorectal cancer and its effect on vascular endothelial growth factor(VEGF) and immune function. Methods： A total of 80 cases of patients receiving chemotherapy after radical resection of colorectal cancer were selected and divided into the control group and the treatment group according to the simple randomization method，40 cases in each group. The control group was given chemotherapy with oxaliplatin，calcium leucovorin and 5-fluorouracil(FOLFOX4)，and the treatment group was additionally treated with Peiyuan Kang'ai tang based on the treatment of the control group. The levels of serum tumor factors and immune function before and after treatment， clinical effects and adverse reactions in the two groups were compared. Results：The total effective rate was 85.00% in the treatment group，higher than that of 65.00% in the control group(P＜0.05). After treatment， the levels of VEGF， serum carcinoembryonic antigen(CEA) and carbohydrate antigen 199 (CA199) in the two groups were decreased when compared with those before treatment(P＜0.05)；the levels of VEGF，CEA and CA199 in the treatment group were lower than those in the control group(P＜0.05). After treatment，the levels of CD3+， CD4+ and CD4+/CD8+ in the treatment group were increased when compared with those before treatment(P＜0.05)，and the level of CD8+ was decreased(P＜0.05)；the levels of CD3+，CD4+ and CD4+/CD8+ in the control group were decreased when compared with those before treatment(P＜0.05)， and the level of CD8 + was increased(P＜0.05). The incidence of adverse reactions was 20.00% in the treatment group， lower than that of 42.50% in the control group(P＜0.05). Conclusion： The application of Peiyuan Kang'ai tang has a significant curative effect in treating patients with postoperative chemotherapy of colorectal cancer，which can inhibit the regeneration of tumor angiogenesis，decrease the levels of tumor markers，improve body immunity，and reduce the incidence of adverse medication reactions.