The coagulation process is the process by which the body’s blood changes from a liquid state to a solid state. The coagulation process is one of the important physiological functions of the body to stop bleeding. If there is a problem with coagulation, the patient will experience bleeding. The coagulation process depends on two coagulation pathways, one is the endogenous coagulation pathway, which is due to vascular injury after the first activation of factor XII, then activation of other factors, and ultimately also activation of fibrinogen, which turns into active fibrin, forming a fibrin clot to stop bleeding. One is the exogenous coagulation pathway. The exogenous coagulation pathway is activated by tissue factors after tissue injury, which then causes a series of activation of other coagulation factors, eventually leading to the transformation of fibrinogen into active fibrin and the formation of fibrin clots, which play a role in hemostasis. If the coagulation process is impaired, the patient will develop coagulation disorders, petechiae of the skin and mucous membranes as well as bleeding of muscles and joints, etc. Common diseases are various types of hemophilia.