Apelin is the endogenous ligand of apelin-angiotensin receptor-like 1(APJ). Apelin/APJ system widely distributed in the body, with high expression level in the vascular system, such as cardiovascular system, pulmonary vascular system. The study found that apelin can regulate vascular tone and inducevascular smooth muscle cell proliferation, promote retinal neovascularization, mononuclear cell adhesion to endothelial cells and hepatic portal vein and coronary collateral formation. In this review, we summarized the actions of apelin regulating blood vessel function and the related diseases (hypertension, pulmonary hypertension, atherosclerosis, glioma, lung cancer, portal hypertension and diabetic angiopathy). Moreover, we revealed the inner connection of apelin with vascular and its related diseases, and show that apelin/APJ can be used as therapeutic targets of vascular disease.