Hemophilia is divided into two types: A and B. Hemophilia A is a bleeding disease caused by the deficiency of coagulation factor VIII, accounting for about 85% of congenital bleeding diseases. According to the report of the joint meeting of the World Health Organization (WHO) and the World Federation of Hemophilia (WHF) in 1990, the incidence of hemophilia A is about 15-20/100,000 people. According to statistics from European and American countries, it is about 5-10/100,000 people. The incidence of hemophilia A in China is about 3-4/100,000 people. Hemophilia B, also known as factor IX deficiency or Christmas disease, has an incidence of about 1.0-1.5/105, accounting for 15%-20% of hemophilia. The gene of factor IX is 34kb long, located on the long arm of chromosome X, with 8 exons and 7 introns. Factor IX is a plasma protein dependent on vitamin K, with a relative molecular weight of 56,000, and is synthesized in the liver. The treatment of hemophilia A and B is similar, using replacement therapy, and plasma, prothrombin complex concentrate (PCC), factor IX concentrate and recombinant factor IX products can be used.