The changes of microcirculation in shock are mainly divided into three phases, including microcirculatory ischemic phase, microcirculatory stasis phase, and diffuse intravascular coagulation phase. The microcirculatory ischemic phase occurs in the early stage of shock, mainly due to the body reflexively releasing some active substances when the effective blood volume is severely insufficient, prompting peripheral vasoconstriction, causing a decrease in capillary blood volume, the main active substance is catecholamines, catecholamines can effectively contract the peripheral capillaries, so as to achieve the effect of increasing the return heart blood flow and maintaining normal blood pressure. The microcirculatory stasis period is due to the early shock is not corrected, will make the surrounding tissues appear hypoxia, ischemia, necrosis and produce acid, this acid can play a significant paralyzing effect on the arterial vessels, so that it is less responsive to catecholamines, so that there is a slight expansion, not much effect on the venous vessels, the venous vessels are still in a state of contraction, resulting in the inflow of blood in the peripheral vessels too much and not enough outflow, and bruising can occur. The period of diffuse intravascular coagulation is due to the persistence of bruising, which can lead to platelets and red blood cells aggregating in the vessels and damaging the vessel walls. This diffuse intravascular coagulation can further damage the vessels and organs, causing a series of serious consequences, which often occurs in the late stages of shock.