Alpha receptors are mainly located in the coronary arteries of the heart, iris radial muscle of the eye, mucosal vessels of the skin, cerebral vessels, and skeletal muscle vessels. When patients take alpha-blockers, they can reduce arterial resistance, increase venous blood volume, reflexively increase heart rate, and increase plasma renin activity. alpha-blockers can also reduce total serum cholesterol levels and LDL levels. The main adverse effect is the first dose of hypotension, but this adverse effect will gradually disappear with the increase of the number of doses. The representative drugs in the clinic are phentolamine mesylate, uradil hydrochloride, terazosin, prazosin, etc.