Inclusion Criteria:
1. Sign the written informed consent form before enrollment;
2. Age ranging from 18 to 75 years old;
3. Be clinically diagnosed with primary immune thrombocytopenia for less than 3 months before randomization;
4. have not received any prior treatments for ITP.
5. Have not received romiplostim treatment;
6. ECOG PS score: 0 - 2;
7. Platelet value \< 30×10\^9/L;
8. The expected survival period at the screening is ≥ 12 weeks;
9. For subjects of reproductive age, agree to take reliable contraceptive measures throughout the study period (including male or female condoms, contraceptive foams, contraceptive gels, contraceptive membranes, contraceptive ointments, contraceptive suppositories, abstinence, and intrauterine device placement, etc.); Female subjects who have undergone hysterectomy, bilateral salpingectomy, bilateral tubal ligation or menopause for more than 1 year, and male subjects who have undergone bilateral vasectomy or ligation are excluded;
10. Voluntarily join this study, sign the informed consent form, and have good compliance.
Exclusion Criteria:
1. Suffering from other secondary thrombocytopenia except ITP, including but not limited to leukemia, thrombocytopenia caused by tumor treatment, myeloproliferative diseases, multiple myeloma, myelodysplastic syndrome, common variable immunodeficiency, and hereditary thrombocytopenia, etc.;
2. Having undergone splenectomy before the first administration;
3. Having received ITP drug treatment (including emergency treatment) before the first administration;
4. Having used drugs with c-Mpl (thrombopoietin receptor) stimulating effects within 4 weeks before the first administration;
5. Having received hematopoietic growth factor preparations (such as granulocyte colony-stimulating factor, macrophage colony-stimulating factor, erythropoietin, interleukin-11, etc.) within 4 weeks before the first administration;
6. Having received antibody drugs (such as rituximab, etc.) within 14 weeks before the first administration;
7. Having received any Chinese herbal medicine or nutritional supplement (except vitamin supplements and mineral supplements) for the purpose of increasing platelets within 1 week before the first administration;
8. Having been diagnosed with arterial thrombosis (such as cerebral thrombosis, transient ischemic attack or myocardial infarction), or having a history or complication of venous thrombosis (such as deep vein thrombosis, pulmonary embolism), or using anticoagulants or antiplatelet drugs at the beginning of screening;
9. Having a history of severe cardiovascular diseases (such as grade III/IV congestive heart failure, arrhythmia or angina pectoris that increases the risk of thromboembolic events, unstable angina pectoris, having undergone coronary artery stent implantation, angioplasty or coronary artery bypass grafting);
10. Secondary thrombocytopenia caused by autoimmune diseases such as antiphospholipid antibody syndrome, systemic lupus erythematosus, Hashimoto's thyroiditis, Even's syndrome and Sjogren's syndrome;
11. Positive results for either human immunodeficiency virus antibody or syphilis antibody screening; positive hepatitis C antibody and HCV-RNA exceeding the upper limit of the study center's laboratory test; positive hepatitis B surface antigen and HBV-DNA exceeding the upper limit of the study center's laboratory test;
12. Having participated in other clinical studies within 3 months before the first administration;
13. Being pregnant or lactating, or having a pregnancy plan;
14. Having fertility and being judged by the researcher as not fully adopting contraceptive measures;
15. Having a history of severe drug allergic reactions or being known to be allergic to glucocorticoids or Nplate® (romiplostim) or the components of QL0911;
16. Unable to comply for mental reasons;
17. Judged by the researcher as not suitable to participate in this trial;
