Phosphodiesterase is a medically important organic compound that belongs to the 2nd messenger molecule and is widely distributed in human cell tissues and molecules, which is important for regulating body fluids and maintaining healthy physiological mechanisms. Phosphodiesterase type 1 has a very good degradation effect on hydrolytic cells and can effectively reduce insulin secretion stimulated by glucose, which is important for the treatment of central nervous and cardiovascular diseases, and is also very effective in improving the immune system. Phosphodiesterase type 2 is found in the cerebral nerve and cardiac areas and has a positive effect on the maintenance of platelets and liver function, especially in the treatment of angina pectoris and hypertension. Phosphodiesterase type 3 is found in the smooth muscle of blood vessels and can dilate blood vessels, even after intravenous administration, and can be effective in relieving heart failure. Phosphodiesterase type 4 has a good degradation and inhibition effect on inflammatory cells, and is usually used as a therapeutic agent for upper respiratory tract inflammation, inhibiting and dilating bronchitis, and also has a good effect on anti-asthma. Phosphodiesterase type 5 can effectively inhibit the formation of blood clots, has a good effect on relieving the pressure of the large arteries, and in recent years has been found to be particularly useful for the function of erectile dysfunction in men. In short, phosphodiesterase has a wide range of uses, but for cardiovascular and pulmonary heart disease can not be the root cause, but only to play a role in relieving, long-term use is easy to form drug dependence.