Inclusion Criteria:  The patients have provided written informed consent prior to enrollment. Men and women greater than or equal to 18 years of age. Diagnosed as ITP secondary to connective tissue diseases (including but not limited to systemic lupus erythematosus, Sjogren's syndrome and rheumatoid arthritis), primary ITP with positive antinuclear antibody but not up to the diagnostic criteria of connective tissue diseases, primary Evans syndrome, Evans syndrome secondary to connective tissue diseases, and primary ITP with positive Coomb's test but not up to the diagnostic criteria of Evans syndrome. Platelet count<30 ×10^9/L at screening. Patients who have previously failed to receive Eltrombopag or Herombopag [poor efficacy (Eltrombopag 75 mg/d or Herombopag 7.5 mg/D, at least 4 weeks), or the efficacy cannot be maintained], or who have contraindications, can not tolerate or refuse Eltrombopag or Herombopag treatment. Treatment for ITP (including but not limited to glucocorticoids, recombinant human thrombopoietin, and other thrombopoietin receptor agonists other than Avatrombopag) must be completed before enrollment, or the dose must be stable or in a phase of reduction within 2 weeks before enrollment. Effective contraceptive measures will be taken during the clinical trial.  Exclusion Criteria:  Patients with active thyroid disease requiring treatment. Patients with any prior history of arterial or venous thrombosis within 3 months, and with any of the following risk factors: cancer, Factor V Leiden, ATIII deficiency, or patients who are using anticoagulants or antiplatelet drugs at the beginning of screening. Those who had received rituximab within 3 months. Patients who had failed to respond to the previous use of Avatrombopag (40mg once a day for more than 4 weeks). Subjects known to be allergic to Avatrombopag or any of its excipients. Patients who had received splenectomy within 3 months or have splenectomy plan within 3 months. Patients with lupus encephalopathy or lupus nephritis. Patients with cataract. Patients with infectious fever (including but not limited to pulmonary infection) within 1 month or with active infection during screening. Existing hepatitis B virus, hepatitis C virus replication or HIV infection. Severe liver dysfunction (alanine aminotransferase or glutamic oxaloacetic transaminase > 3×ULN). Patients with severe cardiac or pulmonary dysfunction. Severe renal damage (creatinine clearance < 30 ml/min). There are surgical planners during the study. History of psychiatric disorder. Pregnant or lactating women or those planning to be pregnant during the trial. Patients with a history of drug/alcohol abuse (within 2 years before the study). Patients that had participated in other experimental researches within one month before enrollment. Any other circumstances that the investigator considers that the patient is not suitable to participate in the trial.