Objective:To study the effects of several herbal medicines on SMMC-7721 liver cancer cells with Fourier transform infrared spectrometer(FTIR). Methods: FTIR was employed to determine the infrared spectra(IRs) of SMMC-7721 liver cancer cells cultivated for 20 h with the extracts of Spica prunellae, Herba houttuyniae, Radix bupleuri and Herba artemisiae scopariae. Cluster analysis of IRs was also performed. Results: IR spectral parameters such as band shape, intensity and frequency of the blank, control and herbal-extract-treated cells were compared. There existed obvious blue shift of ? s(PO 2 -), ? as (PO 2 -) bands, red shift of ? as (CH 3), ?(CH 2) bands on the herbal-extract-treated cells IRs. The decreasing ratio of ? as (CH 3) to ? s(CH 2) peak intensity and the increasing ratio of ? s(PO 2 -) to ?(N-H) peak area indicated the destructive effect of herbal extracts on the membrane structure of SMMU-7721 cells and inhibitory effect on the DNA replication respectively. Cluster analysis successfully discriminated the herbal-extract-treated cells from the blank cells and the liver-oriented medicines from the non-liver-oriented medicine. Conclusion: FTIR provides another fast and effective approach to analyze the changes of cells treated with Chinese herbal medicines, which may help to illuminate the functional mechanism of Chinese herbal medicines.