This is a phase IIb, randomized, double-blind, placebo-controlled, multicenter study to evaluate the efficacy and safety of orelabrutinib in adult subjects with SLE who are receiving standard of care (SOC) therapy.

Inclusion Criteria:

1. have had a detailed understanding of the nature, significance, potential benefits, potential risks, and procedures of the study, and voluntarily signed a written Informed Consent Form (ICF).
2. Males or females aged≥18 and ≤75 years.
3. Have a clinical diagnosis of SLE 6 months prior to signing the ICF, meeting at least 4 of the 11 American College of Rheumatology (ACR) classification criteria for SLE.
4. SLEDAI-2K≥8 at screening.
5. Are on a stable SLE SOC therapy consisting of any of the following medications for a period of at least 30 days prior to the first dose: glucocorticoid, and/or anti-malarials, and/or immunosuppressive agents.
6. Have a positive test for anti-dsDNA antibody (> normal range) and/or anti-nuclear antibody (ANA) and/or anti-Smith antibody at screening.
7. Women of childbearing potential must take a complementary barrier method of contraception in combination with a highly effective method of contraception at screening, throughout the trial, and within 90 days after the last dose of the investigational agent. In this trial.

Exclusion Criteria:

Medical conditions:

1. Pregnant or lactating women, and men or women who have birth plans in the past 12 months.

2. Have neuropsychiatric systemic lupus erythematosus (NPSLE) within 6 months prior to the first dose, including seizures, psychosis, organic brain syndrome, cerebrovascular accident, cranial neuropathy, cerebritis, cerebral vasculitis or lupus headache.

3. Have severe lupus nephritis, or have required hemodialysis or high-dose glucocorticoid within 90 days prior to the first dose.

4. Have autoimmune diseases other than SLE (excluding secondary Sjogren's syndrome).

5. Have a history of any non-SLE disease that has required treatment with oral or intravenous or intramuscular or subcutaneous injection glucocorticoids for more than a total of 2 weeks within the last 24 weeks prior to signing the ICF.

6. Have a history of or current diagnosis of Central Nervous System (CNS) diseases.

7. Have clinically documented cardiovascular diseases that are obviously unstable or not effectively treated.

8. Have significant active lung diseases (e.g., interstitial lung disease, obstructive pulmonary disease).

9. Have severe hepatobiliary diseases.

10. Have a history of malignant neoplasm.

11. Have a history of a major organ transplant or hematopoietic stem cell/marrow transplant.

12. Have known allergies to any component of the investigational agent as described in the Protocol.

    Concomitant medication and surgery:

13. Have received rituximab, epratuzumab, or any other B cell-depleting therapy within 12 months prior to randomization.

14. Have received cyclophosphamide and chlorambucil within 6 months prior to randomization.

15. Have received belimumab, tumor necrosis factor (TNF) blockers, interleukin receptor blockers or other biological agents within 3 months prior to randomization (or 5 half-lives, whichever is longer).

    Lab tests:

16. Have a positive test for human immunodeficiency virus (HIV) antibody.

17. Have a positive test for Hepatitis B Surface Antigen (HBsAg) or hepatitis C antibody, or have a positive test for hepatitis B virus (HBV) DNA by Polymerase Chain Reaction (PCR) if positive for Hepatitis B Core Antibody (HBcAb).

18. Have abnormal tissue or organ function, meeting any of the following at screening:

    • Absolute neutrophil count (ANC) < 1.5 × 10^9/L; hemoglobin < 90 g/L; lymphocyte count < 0.8 × 10^9 /L.
    • Calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation < 45 mL/min/1.73 m2.

    Others:

19. Have other conditions that are not appropriate for participation in the trial as considered by the investigator.