Abstract: Objective To discuss the mechanism of drug serum of Fuzheng Yi′ai decoction on epithelial-mesenchymal transition(EMT) in human colon cancer cell line Lovo by investigating the expression of TGF-β1 and Smad3 and p-Smad3 protein level of TGF-β/Smad signal transduction pathway. Methods The proliferation effect on Lovo cells treated with various concentrations of drug serum was detected by MTT method.A group treated by 5-Fu was used as positive control.Then the expression of TGF-β1 and Smad3 and p-Smad3 protein were detected by Western blot assay. Results According to the results of MTT test,the large concentrations of Fuzheng Yi′ai decoction drug serum restrained the cells proliferation effect was obvious at 24 hours,compared with the median group and small concentration group (P<0.01);the Western blot result revealed that the expressions of TGF-β1,Smad3 and p-Smad3 protein in drug serum group were down-regulated in comparison with the blank group and normal group (P<0.05). Conclusion The drug serum of Fuzheng Yi′ai decoction can inhibit the EMT of Lovo cell correlated with the decreasing expression of TGF-β1.Smad3 and p-Smad3 protein level of TGF-β/Smad signal transduction pathway.