High-salt diet is well recognized as a risk factor for hypertension, and dietary intervention plays a critical role in the prevention of hypertension. The current study investigated the effects of selenium-enriched green tea (Se-GT) and ordinary green tea (GT) on prevention of hypertension of rats induced by high-salt diet, as well as their potential regulatory and mechanism. Our results showed that GT and Se-GT supplementations significantly prevented the increase of blood pressure (BP), activated the phosphoinosmde-3-kinase/protein kinase B (PI3K/Akt) signaling pathway, and regulated the gene expression related to BP, as well as improved the tissue damage like heart, liver, and kidneys. Besides, the key parameters associated with oxidative stress, inflammation and endothelial dysfunction were also altered by GT and Se-GT treatments. Importantly, GT or Se-GT administration adjusted the diversity and composition of the intestinal flora. Moreover, GT and Se-GT supplementations increased the abundance of beneficial bacteria and reduced the abundance of harmful or conditional pathogenic bacteria. More specifically, GT intake specifically and significantly enriched the relative abundance of Paraprevotella and Bacteroides, whereas Se-GT was characterized by specific and significant enrichment for Allobaculum and Bifidobacterium. Our results proved that dietary supplement of GT and Se-GT remarkably improved the vascular functions and effectively prevented tissue damage by regulation of intestinal flora, and thus preventing hypertension induced by high-salt diet.