Abstract: Objective To construct recombined eukaryotic expressional vector pcDNA 3.1(+)-HRE-Egr-1-Dbait by hypoxia and radiation dual-induced promoter and to observe its radiosensitivity effect on HeLa cells in hypoxia response. Methods Egr-1 promoter elements were amplificated from C57BL/6 nude mice by PCR, Dbait oligonucleotide and HRE enhancer elements were gained by chemical synthesis.The recombined plasmid pcDNA 3.1(+)-HRE-Egr-1-Dbait was constructed by gene reconstruction.pcDNA3.1(+)-HRE-Egr-1-Dbait was transfected into HeLa cells. Colony Formation Assay was used to the detect the radiosensitivity effect transfectants. Results The recombinant plasmids pcDNA 3.1(+)-HRE-Egr-1-Dbait was constructed and identified by enzyme digestion and sequencing. The D0, Dq, SF2，α/β value of HeLa cells in normal oxygen were 1.98, 0.93, 0.52, 11.12, respectively. The D0, Dq, SF2 value in hypoxia were 1.74,1.46, 0.43, 15.82. OER value was 0.88. Conclusion We successfully constructed the combined eukaryotic expressional plasmid vector pcDNA3.1(+)-HRE-Egr-1-Dbait characterized by radiation and hypoxia dual-induced promoter. And this expression vector could significantly increase the radiosensitivity of human cervical cancer HeLa cells in hypoxic response.