Hemocoagulation is the coagulation of blood, which means that human blood has the function of changing from liquid state to solid state, and hemocoagulation is also an important physiological function of the human body to stop bleeding. If there is a problem with blood coagulation, the patient will have obvious bleeding symptoms, such as hemophilia patients is due to blood coagulation disorders, the patient is not easy to stop bleeding after trauma since childhood, subcutaneous or muscle, joints bleeding and so on. Blood coagulation is achieved through the amplification of a series of coagulation factors. There are two types of coagulation pathways in the human body: exogenous coagulation pathway and endogenous coagulation pathway. Disorders of either coagulation pathway will lead to blood coagulation dysfunction, which will be manifested by subcutaneous petechiae, bleeding from the nose, gums, or bleeding that is not easy to stop after traumatic injury or surgery. Generally, it is possible to find out which coagulation pathway is in trouble through routine coagulation tests. Generally speaking, APTT is the index to reflect the endogenous coagulation pathway, and PT is the index to reflect the exogenous coagulation pathway. No matter which kind of coagulation pathway is in trouble, it can be detected through coagulation routine.