Objective: To investigate the effect of peroxiredoxin 1 (Prx-1) inhibition on radiosensitivity of hepatocellular carcinoma (HCC) cells. Methods: Using human HCC HepG2 cells, the radioresistant HCC cells (RR-HepG2) were induced by fractionated irradiation with ascending radiation dose levels. In RR-HepG2 cells and their parental HepG2 cells, the Prx-1 expression was examined, and after undergoing the same radiation treatment, the survival rate and the invasion and migration abilities were determined. Then, in these two types of cells after transfection with the plasmids bearing shRNA-Prx-1, the above parameters were determined again. Results: In RR-HepG2 cells compared with their parental HepG2 cells, both Prx-1 mRNA and protein expressions were significantly increased; the survival rate, and invasion and migration abilities were significantly increased after radiation treatment (all P<0.05). After shRNA-Prx-1 transfection, in both types of cells compared with their counterparts transfected with negative control sequences, both Prx-1 mRNA and protein expressions were significantly decreased; the survival rate, and invasion and migration abilities were significantly decreased after radiation treatment (all P<0.05). Conclusion: The decreased radiosensitivity in HCC cells may probably be associated with Prx-1 expression, and regulating its expression could potentially be an effective approach for enhancing radiosensitivity of HCC cells.