Abstract: To explore the role of quercetin in improving TNF-α-induced cells′ models with intestinal barrier dysfunction,we established the epithelial barrier dysfunction model through Caco-2 monolayer cells incubated with 200 ng/mL TNF-α for 24 h.Then the models were treated with quercetin (5,15,30 μ mol/L) by which the permeability of epithelial monolayers,their expression and function of Claudin-1 and Occludin were affected.The results showed that,compared with the control group,epithelial permeability was increased and the phosphorylation components in tight junction (TJ) proteins of claudin-1 and occludin were markedly reduced in TNF-α group.After monolayers treated with quercetin,their barrier function,phosphorylation components of Claudin-1 and Occludin and the whole cell proteins of Occludin were all upregulated in a dose-dependent manner.So quercetin could improve the intestinal barrier function by regulating their structure and function of TJ proteins.