Objective To explore the lipopolysaccharide (LPS)-induced changes of heat shock protein A12B (HSPA12B) expression and its effect on the permeability of human umbilical vein endothelial cells (HUVECs). Methods The HUVECs cultured in vitro were divided into four groups: control group (without any treatment); LPS group (1 μg/mL LPS); LPS +pIRES2-EGFP-HSPA12B-3Flag group(The HSPA12B gene overexpression plasmid was transiently transfected into HUVECs and then LPS of 1 μg/mL was added); and LPS+pIRES2-EGFP-3Flag group (The negative control plasmid was transiently transfected into HUVECs and then LPS of 1 μg/mL was added). The transendothelial electrical resistance (TEER) of HUVECs was measured by MERSST×01 Electrode. The expression of VE-cadherin was studied by flow cytometry. RT-PCR and Western blotting analysis were used to examine the expression changes of HSPA12B mRNA and protein in HUVECs stimulated with LPS at various time points. Results It was showed that after stimulated with LPS, HSPA12B mRNA and protein were gradually upregulated, and peaked at 12 h. HSPA12B significantly increased the TEER value of HUVECs (P<0.001), and it could completely offset the decline of TEER value induced by LPS(P<0.001). Besides, HSPA12B could cause upregulation of VE-cadherin expression. Conclusion HSPA12B can reduce the permeability of vascular endothelial cells by up-regulating the expression of VE-cadherin, thus protecting the vascular endothelial barrier function of endothelial cells.