Objective:To study the effects of Ruyiping medicated serum on proliferation and invasion of mouse mammary carcinoma 4T1 cells,and discuss its mechanism. Methods①The medicated serum of Ruyiping with different concentrations(10%,20%,30% and 40%) were prepared,and the blank serum at same concentrations were taken as the control. The effect of medicated serum on the viability of 4T1 cells was detected by methylthiazolyldiphenyl-tetrazolium(MTT)assay to screen the optimum concentration and exposure time. ②The cells were divided into the blank control group,TGF-β1 control group,Ruyiping medicated serum groups with low(10%)- and high(20%)-concentration. Except the blank control group,the cells in the other groups were all given the pre-treatment with TGF-β1 at concentration of 2 mg/L for 3 hours. And then the cells were treated with blank serum or medicated serum for 48 hours respectively. The effect of medicated serum on the invasion of TGF-β1 pre-treated 4T1 cells was detected Transwell test. The effects of medicated serum on the expressions of Smad4 and Smad7 in TGF-β1 pre-treated 4T1 cells were determined by Western blotting and Real-time PCR.  Results:①The Ruyiping medicated serum significantly inhibited the proliferation activity of 4T1 cells. 10% and 20% were taken as the optimum concentrations,and 48 hours was taken as the optimum exposure time for the experiment. ②The Ruyiping medicated serum significantly inhibited TGF-β1-induced high invasion of 4T1 cells,with a concentration-dependent manner. The results of Western blotting and Real-time PCR showed that,the Ruyiping medicated serum obviously reversed the high mRNA and protein expressions of Smad4 induced by TGF-β1,but no effects on the up-regulated mRNA and protein expressions of Smad7 were observed.  Conclusion:Ruyiping medicated serum could inhibit the proliferation and invasion of 4T1 cells. Its mechanism may be associated with the regulation on the expressions of related factors in TGF-β/Smads signal pathway.