Abstract： Objective: The aim of our study was to investigate the effect of diallyl trisulfide (DATS) combining radiation on DNA injury-repair of Esophageal cancer EC109 cells. Methods: Using 10 and 20 μg/mL DATS on EC109 cells, and taking X-ray radiation 24 h later. Investigate the radiosensitization effect of DATS on EC109 cells by clone formation, and the mechanism of DNA injury-repair by Comet Assay. Results: The clone formation resulted that DATS had radiosensitization effect on EC109 cells. Radiosensitization enhancement ratios of 10 and 20 μg/mL DATS in combination with radiation were 1.55,1.64 (Do) and 1.43,1.75 (Dq) respectively. In the comet assay, the TM (tail moments) of 20 μg/mL DATS combining radiation group lines at 0 h, 2 h, 6 h and 24 h were 7.16 ± 2.61,3.65 ± 2.06,2.09 ± 0.83,1.45 ± 1.37 respectively. They were slightly increased than radiation group (0.95 ± 0.65, 0.11 ± 0.07, 0.1 ± 0.05, 0.11 ± 0.08) and DATS group (1.81 ± 1.23,1.58 ± 1.40, 0.45 ± 0.25,0.60 ± 0.40) (P < 0.01). The result showed that DATS combining radiation had the effect of increasing DNA damage and inhibiting DNA repair on EC109 cells. Conclusion: DATS has radiosensitization effect on Esophageal cancer EC109 cells. And the effect is probably related with DNA injury-repair.