The aim is to investigate the effects of AS1411 on radiosensitivity and the relative mechanism on uterine cervical cancer HeLa cells. γ-H2AX immunofluorescence technique was applied to observe the DNA damage of HeLa cells; change in cell cycle and cell apoptosis rate was detected by flow cytometry. The results show that γ-H2AX foci of HeLa cell increase significantly after being pretreated by AS1411; AS1411 pretreatment does not influence the cell cycle arrest caused by radiation, but it does accelerate the apoptosis rate of HeLa cells induced by radiation. By increasing the DNA double-strand breaks and inducing cell apoptosis of the HeLa cells caused by radiation, AS1411 can enhance the radio sensitization of HeLa cells. However, the mechanism of the radiosensitizing effect is uncorrelated with cell cycle.Cited