Nitroglycerin is widely used in the treatment of coronary artery disease. Its mechanism of action is: dilating the veins, reducing the amount of return blood, decreasing the left ventricular preload, reducing the work of the left ventricle during contraction, decreasing oxygen consumption, etc.; improving the subendocardial myocardial ischemia due to the decrease of the left ventricular diastolic filling pressure, increasing the perfusion step difference of the diastolic coronary artery; dilating the coronary artery, increasing the coronary blood flow, while nitroglycerin can also promote the production of vascular At the same time, nitroglycerin can also promote the production of preprocycline (PGI2), which has a vasodilating effect, and inhibit the release of thromboxane A2 (TXA2), which has a strong vasoconstrictive effect, by endothelial cells. Because of its rapid onset of action, nitroglycerin is commonly used in angina attacks and acute myocardial infarction. Since the absorption effect of sublingual administration is faster than that of gastrointestinal absorption, sublingual administration of nitroglycerin 0.6~1.8 mg is commonly used in emergency situations. However, continuous sublingual administration of multiple tablets of nitroglycerin may cause a drop in blood pressure and should be noted.