Coagulation is the ability of the human blood to change from a liquid state to a solid state. Normal coagulation is the basic condition to ensure that the human body does not suffer from bleeding disorders. Clinically, the coagulation function of the human body is mainly realized through the endogenous and exogenous coagulation pathways. No matter which coagulation pathway is impaired, the human body will show obvious symptoms of bleeding. In patients with hemophilia, the endogenous coagulation pathway is impaired due to a decrease in the activity of coagulation factor VIII, resulting in significant bleeding symptoms, often manifesting as bleeding after trauma since childhood, skin and mucous membrane petechiae, and also large hematomas in muscles and joints, which are often left with joint deformities after the hematoma is absorbed. If the coagulation function is impaired, it is necessary to go to the hospital for timely examination.