Objective To study the expression of human Runt-related transcription factor 1 (RUNX1) in rat airway epithelial cells stimulated by cigarette smoking extract (CSE), and explore the role of RUNX1 in regulating epithelial-mesenchymal transition (EMT). Methods Primary rat bronchial epithelial cells were cultured by enzyme digestion and stimulated with different concentrations of CSE. The viability of cells was detected by CCK-8 to explore the appropriate concentration of CSE. After the cells were treated with CSE, the Runx1 interference and overexpression vectors were constructed and transfected into the cells to silence or overexpress the Runx1 gene. Immunocytochemical method was used to detect RUNX1 expression and Western blot analysis was used to detect the expression of RUNX1, nuclear factor-κB (NF-κB), Snail, E-cadherin, and vimentin. Results The survival rate of bronchial epithelial cells could be reduced by CSE, and the degree of reduction was directly positively correlated to the concentration of CSE. After CSE stimulation, the expression level of E-cadherin in primary rat bronchial epithelial cells decreased significantly (P<0.05); the expression levels of RUNX1, NF-κB, Snail and vimentin significantly increased (P<0.05). After interfering with RUNX1 gene, the expression level of E-cadherin was up-regulated (P<0.05), and the expression levels of NF-κB, Snail and vimentin were down-regulated (P<0.05). After overexpression of RUNX1 gene, the expression level of E-cadherin decreased (P<0.05), and the expression levels of NF-κB, Snail and vimentin increased (P<0.05). Conclusions CSE promotes the expression of RUNX1 in rat airway epithelial cells. RUNX1 might regulate EMT process by involving in the regulation of NF-κB /Snail expression.