Objective:To investigate the effect of POLⅠ (DNA polymeraseⅠ)on the radiosensitivity of human esophageal cancer cells (ECA-109)and their sensitivity to cisplatin. Methods:The plasmid expressing shRNA against POLⅠ was constructed and transfected into ECA-109 cells. The transfection efficiency was evaluated by fluorescence microscopy. POLⅠ expression was detected by Real-time Fluorogenic Quantitative PCR. The cell sensitivity to X-ray was detected by colony formation assay. MTT was used to determine the sensitivity of ECA-109 cells to cisplatin. Results:After successful transfection of constructed shRNA-POLⅠ gene into ECA-109 cells,a large number of fluorescent particles were observed in fluorescence inverted microscope. The expression of POLⅠ in mRNA was significantly reduced (P < 0.05). The ability of radiosensitivity was enhanced. On the other hand,sensitivity to cisplatin was enhanced (P < 0.05). Conclusion:ShRNA-POL I in human esophageal cancer cells could enhance their radiosensitivity and sensitivity to cisplatin.