The main antihypertensive drugs that dilate blood vessels are as follows: 1. calcium antagonists, which can dilate arteries to play a role in lowering blood pressure. 2. sodium nitroprusside, which can dilate small arteries and dilate pulmonary arteries to play a role in lowering blood pressure, with a fast onset and short duration. 3. nitrates, which can directly dilate blood vessels, dilate smooth muscle of blood vessels, and also dilate venous vessels. 4. hydrazinepyridazine, which can be taken orally to dilate blood vessels. It is mainly used in patients with renal hypertension and relatively high diastolic blood pressure. When using vasodilating antihypertensive drugs, attention should be paid to monitoring blood pressure to prevent it from falling too low.