• Age 12-18 years old, male or female

• Conform to the diagnostic criteria of persistent or chronic immune Thrombocytopenia (ITP)

• With a platelet count of \<30 X 10\^9/L measured within 2 days prior to administration（Platelet counts were measured at least 2 times during screening (at least 1 week apart) with platelets\<30 X 10\^9/L）

• Failure or recurrence of previous hormonal therapy or hormone dependence

• The previous emergency treatment of ITP (e.g. methylprednisolone, platelet transfusion, IVIG transfusion) must be completed at least 2 weeks before the first administration

• Signed and dated written informed consent

• With Liver and kidney function\<1.5×upper limit of normal， such as ALT、AST，BUN，Cre，etc.

• ECOG physical state score ≤ 2 points

• Cardiac function of the New York Society of Cardiac Function ≤ 2

• Patients receiving maintenance treatment (including corticosteroids (less than or equal to 0.5mg/kg prednisone), TPO receptor agonists, etc.) must have a stable dose at least 4 weeks before the first administration, and azathioprine, danazol, cyclosporin A, tacrolimus, sirolimus, etc. must be stopped at least 4 weeks before the first administration; The end of rituximab treatment was\>3 months；More than 6 months after splenectomy.