The present study aimed to investigate the effects of histone deacetylase 6 (HDAC6) inhibitor Cay10603 (Cay) on high glucose (HG)-stimulated human retinal pigment epithelium (RPE) cells and its underlying mechanisms. ARPE-19 cells were cultured under normal glucose (NG) or high glucose (HG) conditions. The results revealed that HDAC6 was upregulated in HG-stimulated ARPE-19 cells. Cay treatment caused a decrease in intracellular reactive oxygen species (ROS). The levels of malondialdehyde (MDA) and myeloperoxidase (MPO) were reduced accompanied by increase in the activities of superoxide dismutase (SOD) and catalase (CAT) after treatment with Cay. Besides, Cay decreased the levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), IL-6 and monocyte chemoattractant protein-1 (MCP-1) in supernatant. Meanwhile, the apoptotic rate in Cay-treated ARPE-19 cells notably reduced, coupled with an upregulation in Bcl-2 expression and a downregulation in cleaved caspase-3 and cleaved caspase-9 expression. Cay decreased the expression of phospho (p)-NF-kappa B p65, p-I kappa B-alpha, NLRP3, cleaved caspase-1 and ASC while increased the expression of NF-kappa B p65 (cytoplasm). Taken together, these findings demonstrated that Cay suppressed HG-induced oxidative stress, inflammation and apoptosis via regulating NF-kappa B and NLRP3 inflammasome pathway in HG-induced ARPE-19 cells, suggesting that Cay might be a therapeutic agent for the treatment of diabetic retinopathy.