Abstract: Objective To explore radiosensitizative effect on esophageal cell line TE-1 by buthionine sulfoximine (BSO) combined with radiation. Methods Colorimetric 3-［4，5-dimethy thiazol-2-yl］-2，5-diphenyltetrazolium bromide (MTT)assay was used to study the inhibitory effect and rediosensitivity on proliferation of TE-1 cell treated with BSO and radiation.Additionally，flow cytometry，reverse transcription polymerase chine reaction (RT-PCR)and Western blot were also conducted to observe the influence of BSO and radiation on cell apoptosis，cell cycle and the expression of manganese superoxide dismutase (MnSOD)protein. Results With a clear dose and time effect，BSO could definitely inhibit the proliferation of esophageal cell and enhanced radiosensitivity of TE-1 cells.Flow cytometry analysis obviously increased cell apoptosis and G2/M phase in the effect of BSO and radiation.The expression of MnSOD mRNA or protein was decreased in the action of BSO and radiation by using RT-PCR and Western blot. Conclusion BSO could enhance rediosensitivity of esophageal cancer cell by its effect on cell cycle，MnSOD m RNA or protein.