〔Abstract〕 Objective To investigate the protective effect and mechanism of miR-155 on nucleus pulposus cells of rats. Methods Rat nucleus pulposus cells were cultured. miR-155 expression was detected after interleukin-1β(IL-1β) treatment and transfection. Cells were divided into Control group, IL-1β group(model group), IL-1β+miR-155 mimic group and IL-1β+miR-155 inhibitor group. Apoptosis rate was detected by flow cytometry. The expression levels of interleukin-6(IL-6), inducible nitric oxide synthase(iNOS) and interleukin-10(IL-10) were detected by ELISA. The contents of lactate dehydrogenase(LDH), superoxide dismutase(SOD), malondialdehyde(MDA) and glutathione(GSH) were detected by the kit. Western blot was used to detect the protein expression levels of Caspase-3, Caspase-9, p65, p-p65 and tumor necrosis factor α(TNF-α). Results IL-1β inhibited the expression of miR-155. Compared with the control group, the apoptotic rate of nucleus pulposus cells, Caspase-3, Caspase-9, IL-6, iNOS, LDH, MDA, NF-κB p65 and TNF-α expression in the model group all increased significantly, while IL-10, SOD and GSH all decreased significantly. Compared with the model group, miR-155 mimic reversely regulated the above indicators. Conclusion MiR-155 inhibits apoptosis, inflammation and oxidative stress in nucleus pulposus of rats, which may be related to the inhibition of NF-κB signaling pathway activation.