〔Abstract〕 Objective To investigate the effect of sodium selenite on the biological behavior of lung cancer cells and the specific mechanism of its effect on lung cancer apoptosis through the NF-κB signaling pathway. Methods CCK-8 cell proliferation assay and cell scratch assay were used to observe the proliferation and migration of lung cancer cells. Flow cytometry, qPCR and Western blot were used to detect the apoptosis of lung cancer cells and the expression of Bcl-2, Bax, NF-κB, p-NF-κB, IkBα, p-IkBα in lung cancer cells respectively. The distribution of p-NF-κB in lung cells was observed by immunofluorescence assay. Results The results of CCK-8 cell proliferation assay and cell scratch assay showed that lung cancer cell proliferation and migration were significantly inhibited by sodium selenite. The results of Flow cytometry showed that the apoptosis of lung cancer cells significantly increased after sodium selenium treatment. Compared with the control group, the expression levels of p-NF-κB, p-IkBα, Bcl-2 protein and Bcl-2 mRNA in the sodium selenite group were down-regulated, while the expression of Bax protein and mRNA were up-regulated. The results of immunofluorescence experiments showed that sodium selenite could inhibit the phosphorylation level of NF-κB. The qPCR results showed that sodium selenite and BAY11-7082(NF-κB inhibitor) could down-regulate the expression level of Bcl-2 mRNA, while up-regulate the expression of Bax mRNA. Conclusion Sodium selenite may inhibit proliferation and migration of lung cancer cells and induce apoptosis by inhibiting the NF-κB signaling pathway.