Objective To observe the anti-tumor action of Chang'aishu and its influence on the expression of the Ki67 and PCNA. Methods Forty Balb/c mice with CT-26 colorectal cancer were randomly divided into four groups, including the control group (normal saline, 0.6 mL), the chemotherapy group (Xeloda 205.5 mg/kg), the high dose group (Chang'aishu 51.38 g/kg) and the low dose group (Chang'aishu 17.13 g/kg). Each group of mice was treated with intragastric administration every two days. After 15 days, the anti-tumor rate was calculated and the expression of Ki67 and PCNA were analyzed by immunohistochemistry. Results Compared with the control group, inhibitive rate of the chemotherapy group, the high dose group and the low dose group was 43.35%, 29.48% and 13.30%, respectively. Compared with the control group, the treatment group showed statistical significant difference in Ki67 and PCNA (P<0.05, P<0.01). Conclusion Chang'aishu had inhibition effect on the growth of colorectal cancer, which may be related to down-regulating the expression of Ki67 and PCNA.