Objective:To investigate the effect of decreasing DKC1 gene expression on radiosensitivity of HeLa cells.Methods:A cell model with low expression of DKC1 gene was established by shRNA technology with lentivirus as vector, and the interference efficiency was verified by RT-PCR and Western blot assay. Cells were divided into two groups of interference (Lv-shDKC1) and its negative control. Telomerase activity was detected by TRAP-ELISA, and telomere length was measured by Real-time PCR. Cell survival was obtained through clone formation assay and fitted by multi-target single-hit model, and radiobiological parameters ( D0, Dq, N, SF2) and radiosensitization ratio (SER) were calculated. Results:After DKC1 interfering, the expression levels of mRNA and protein of DKC1 in HeLa cells were significantly decreased by (71.330±4.112)% ( t=25.53, P<0.05) and (35.520±3.804)% ( t=4.833, P<0.05), respectively. Compared with the blank control group and negative control group, the telomerase activity of Lv-shDKC1 group decreased significantly from 0.900±0.044 and 0.897±0.031 to 0.713±0.021 ( F=31.44, P<0.05), the relative telomere length was significantly decreased from 4.233±0.306 and 4.633±0.379 to 2.667±0.404 ( F=39.15, P<0.05). The telomerase activity and relative telomere length of blank control group and Lv-shDKC1 negative control group had no significant difference( P>0.05). SF2 in the interference group (0.571±0.006) was significantly lower than that of the blank control group (0.861±0.009) and the Lv-shDKC1 negative control group (0.807±0.002) ( F=1812, P<0.05), and the radiosensitization ratio (SER) of shDKC1 interference was 1.508. Conclusions:Downregulation of DKC1 in human cervical cancer HeLa cells enhances the radiosensitivity through inhibiting the activity of telomerase and shortening the length of telomere. DKC1 gene may become a new target of radiosensitization.