Hemophilia A/B is a hereditary bleeding disorder. Bleeding is an important clinical feature in patients with hemophilia, and is common spontaneously, after minor trauma where bleeding is difficult to stop or after trauma or surgery with severe bleeding. The sites of bleeding are commonly found in weight-bearing large joints (e.g. knees, elbows, ankles, etc.) and muscles/soft tissues (lumbar square muscles, upper limb muscles, lower limb muscles, etc.); internal bleeding (e.g. intra-abdominal, retroperitoneal, urinary, digestive, aspiration tract, etc.); skin and mucous membrane bleeding (e.g. skin bruising, nasal bleeding, oral bleeding, gum bleeding, etc.). Fatal bleeding includes intracranial bleeding, neurological bleeding, neck bleeding and unprepared trauma, surgical bleeding, etc. According to the severity of bleeding of patients and their plasma FⅧ activity (FⅧ:C), FⅨ activity (FⅨ:C) levels, domestic hemophilia A/B is divided into 4 types: 1. Heavy (activity <1%) shows spontaneous and repeated bleeding, seen in joints, muscles, internal organs, skin, mucous membranes, etc.; 2. Medium (activity 1-5%) shows spontaneous bleeding, mostly after trauma and surgery with severe bleeding. 3.Light type (activity 5-25%) shows no spontaneous bleeding and obvious bleeding after trauma and surgery; 4.Subclinical type (activity 25-45%) shows abnormal bleeding often after trauma and surgery.