Aim That Ox-LDL induced endothelial inflammation response then promoted monocyte and macrophage adhesion is an essential pathophysiological process of atherosclerosis. Hydrogen sulfide is a novel gasotransmitter and exhibits anti-atherosclerotic and anti-inflammation effects. The present study investigated the role of Krüppel-like factor 6 (KLF6) in protection of H₂S on ox-LDL induced endothelial inflammation. Methods Cystathionine γ lyase (CSE) protein expression, H₂S generation by fluorescence probe were assayed after ox-LDL stimulated in human aortic endothelial cells (HAEC). Then, quantitative real-time PCR were used for measuring the changes of Krüppel-like factors mRNA while treated with H₂S donor or overexpression CSE gene by adenovirus. And then, assayed the inflammatory factors changes and monocyte adhesion to HAEC while knockdown the KLF6. At last, chromatin immunoprecipitation (ChIP) assay were used for determining the DNA binding activity of KLF6 after H₂S treatment. Results Using Western blot to measure the CSE protein expression, H₂S fluorescence probe to identify the endogenous H₂S generation, it found that ox-LDL down-regulated endothelial endogenous CSE/H₂S system in a dose-dependent and time-dependent manner.Ox-LDL lowered KLF6 but increased KLF10 mRNA expression; H₂S donor (NaHS) reversed the KLF6 and KLF10 mRNA changes by ox-LDL induction. In this cellular model, other KLF family mRNA is not changed. Next, it confirmed H₂S donor or CSE overexpression up-regulated KLF6 protein expression. H₂S reduced inflammatory factors-ICAM-1, VCAM-1 expression and monocyte adhesion to endothelium induced by ox-LDL, knockdown KLF6 blocked the H₂S action. It confirmed that H₂S donor decreased DNA binding activity of KLF6 to CXCL2, IL-8 and ATG7 promoter. Conclusion Ox-LDL down-regulated endothelial CSE/H₂S system. H₂S donor treatment or overexpression CSE reduced ox-LDL induced inflammation response by KLF6.