The study start on June 30, 2018. The Severe(F Ⅷ<1%) hemophilia A children without F Ⅷ inhibitor combining were recruited to Test the concentration of the drug in the blood to provide better treatment.

Through the integration of two technologies, pharmacokinetics and comprehensive evaluation system, we can improve the individualized prevention and treatment of hemophilia in Chinese children and achieve precise customization of treatment plans. Rational use of medical resources, but also fully achieve the prevention and treatment goals.

Inclusion Criteria:

• FⅧ<1% ,
• 1-14years old,
• There have been at least one history of bleeding in any joint of the knee, elbow, or ankle.
• A blood product containing FVIII is applied.
• There were no inhibitors at the time of enrollment, and there was no inhibitor-positive history and family history.
• Clinical visits are available on a regular basis and data is available, and preventive treatment is available prior to enrollment.
• The child was enrolled in the group and the guardian agreed.

Exclusion Criteria:

• Combining other disease researchers believes that it is not suitable for enrollment.
• FVIII inhibitor was found.
• Refuse to participate in research