Microcirculation is a type of blood circulation between the microvessels and microarterial veins. The composition of the microcirculation varies among organs and tissues in the human body with different structural functions. Typical microcirculatory structures include posterior microarterioles, microarterioles, precapillary sphincters, blood-permeable capillaries, true capillaries, and microveins. There are three types of blood flow pathways in the microcirculation, including the nutrient pathway, the direct interception pathway, and the arterio-venous pathway. The basic function of microcirculation is blood circulation and material exchange between tissues. Material exchange takes place between tissues and cells through cell membranes and tissue fluid, while material exchange takes place between tissue fluid and blood through capillary walls. Microcirculation is an important place for the exchange of substances and gases between the human body and the external environment, and plays a very important role in maintaining the metabolism of tissue cells and the homeostasis of the internal environment.