Inclusion Criteria:  Men and women greater than or equal to 18 years of age. Participants diagnosed with chronic primary immune thrombocytopenia (greater than or equal to 12 months duration) and an average of 2 platelet counts < 30x10^9/L at least 7 days, do not have evidence of other causes of thrombocytopenia (e.g., pseudothrombocytopenia, myeloid fibrosis). The physical exam should not suggest any other diseases which may cause thrombocytopenia other than ITP. Previous treatment with Eltrombopag or rhTPO was ineffective (platelet count < 30x10^9/L after treatment, or platelet count increased less than twice the baseline value, or bleeding). Prothrombin time/International Normalized Ratio and activated partial thromboplastin time must have been within 80% to 120% of the normal range with no history of hypercoagulable state. Good compliance.  Exclusion Criteria:  Patients diagnosed with secondary immune thrombocytopenia or a history of systemic lupus erythematosus and antiphospholipid antibody syndrome. A history of myelodysplastic syndrome (MDS), lymphoproliferative disease, myelodysplastic tumor, and leukemia. A history of arterial or venous thrombosis (stroke, transient ischemic attack, myocardial infarction, deep vein thrombosis or pulmonary embolism) within 3 months before screening, and the following 2 or more risk factors: including estrogen hormone replacement therapy or contraceptive therapy, smoking, diabetes, hypercholesterolemia, high blood pressure medications, cancer or any other family history of arterial or venous thrombosis, or patients who were taking anticoagulants or antiplatelet drugs at the beginning of the screening. Participants with a history of significant cardiovascular disease (e.g., congestive heart failure [CHF] New York Heart Association Grade III, arrhythmia known to increase the risk of thromboembolic events [e.g., atrial fibrillation], coronary artery stent placement, angioplasty, coronary artery bypass grafting). Hereditary prethrombotic syndromes (e.g., thrombin factor V Leiden mutation, prothrombin G20210A mutation, or hereditary antithrombin (ATIII) deficiency). Participants with concurrent malignant tumor diseases. Blood creatinine >1.2 times the upper limit of normal value (ULN) . Participants with known allergy to avatrombopag or its excipients. Women who are pregnant or who intend to become pregnant in the near future are excluded.