Abstract: Melatonin is a neuroendocrine hormone, which is synthesized primarily by the pineal gland. The synthesis and secretion of melatonin are regulated by light intensity. It has been found that melatonin has functions in regulating the sleep cycle, antioxidant and anti-inflammatory. Melatonin has also been shown to regulate lipid and glucose metabolism. Recent research suggests that melatonin plays an important role in various cardiovascular diseases, including hypertension, myocardial ischemia-reperfusion injury, pulmonary hypertension, myocardial chronic intermittent hypoxic injury, vascular diseases and valvular heart diseases. In this paper, the relationship between melatonin and cardiovascular diseases is described.