Objective:To study the effect of Sanjie Xiaoliu Recipe on transplanted tumors in breast cancer mice through in vivo experiments, in order to explore the efficacy and mechanism of Sanjie Xiaoliu Recipe on breast cancer patients. Methods:45 BaL B/c female mice were selected to establish the transplanted tumor model of breast cancer. All the transplanted tumor models of breast cancer mice were randomly divided into five groups: the control group (intragastric administration of normal saline), the low, medium and high dose group of Sanjie Xiaoliu Recipe (intragastric administration of different doses of Sanjie Xiaoliu Decoction), and the paclitaxel group (intraperitoneal injection of paclitaxel). After 24 days of continuous administration, the diet and activities of mice were observed; the body weight, weight and volume changes of transplanted tumor mice were recorded, and the tumor inhibition rate was calculated. Western blot was used to detect the expression of epithelial mesenchymal transformation related proteins (E-cadherin, N-cadherin, Vimentin) in the transplanted tumor tissues of mice in each group.Results:(1) The food intake and activity status of mice treated with Sanjie Xiaoliu Recipe were less affected by the transplanted tumor of breast cancer. (2) The volume and weight of transplanted tumor in the treat groups were smaller than those in the control group (all P<0.01), and the volume of transplanted tumor in the middle dose group of Sanjie Xiaoliu Recipe was smaller than that in the low dose group ( P<0.05). The tumor inhibition rates among the treatment groups were: Sanjie Xiaoliu Recipe medium dose group 52.4%, paclitaxel group 40.3%, Sanjie Xiaoliu Recipe low dose group 39.5%, Sanjie Xiaoliu Recipe high dose group 34.1%. (3) The results of Western blot showed that the expression level of E-cadherin in the transplanted tumor tissue of the treat groups was higher than that in the control group, and the expression levels of N-cadherin and Vimentin were lower than that in the control group, with statistically significant difference (all P<0.05). Conclusions:The Sanjie Xiaoliu Recipe can improve the weakness and reduced consumption of breast cancer mice, which can inhibit the tumor mass growth in mice to a certain extent. Its mechanism may be that Sanjie Xiaoliu Recipe can inhibit the epithelial mesenchymal transformation of breast cancer and the invasion and metastasis of breast cancer.