Abstract： Objective:To study the changes of proliferation and oxidation indexes of Cochlear hair cell line (HEI-OC1 cells) exposed to ethylbenzene.Methods:From July to December 2019, 11 groups with ethylbenzene concentrations of 0, 30, 60, 90, 300, 600, 900 μmol/L and 3, 6, 9, 10 mmol/L, were used to determine the proliferation activity of HEI-OC1 cells exposed to ethylbenzene for 24 hours, and the cells were treated with 0, 1, 2, 4, 8, 16, 32, 64 mmol/L ethylbenzene for 24 hours, then the 50% inhibitory concentration of ethylbenzene was calculated. After HEI-OC1 cells were exposed to 0, 6, 9 and 12 mmol/L ethylbenzene for 24 hours, the malondialdehyde (MDA) content, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were measured.Results:Compared with 0 mmol/L concentration group, the survival rate of HEI-OC1 cells at 6, 9, 12 mmol/L concentration was significantly decreased ( P<0.01) . The 50% inhibitory concentration of ethylbenzene on HEI-OC1 cells was 12.86 mmol/L ( R2=99.05) . There were significant differences in SOD and GSH-Px activity in HEI-OC1 cells treated with ethylbenzene at different concentrations (0, 6, 9, 12 mmol/L) for 24 hours ( F=65.11, 6.48, 22.85, P<0.05) . Compared with 0 mmol/L concentration group, the MDA content of HEI-OC1 cells was significantly increased in 9 and 12 mmol/L concentration groups, the SOD activity was significantly decreased in 12 mmol/L concentration group, and the GSH-Px activity was significantly decreased in 6 and 12 mmol/L concentration groups. Conclusion:Ethylbenzene can inhibit the proliferation of HEI-OC1 cells and cause oxidative damage.