Eligibility Criteria:
Inclusion Criteria:
* Patients who meet the 2015 International Consensus Diagnostic Criteria for Neuromyelitis Optica Spectrum Disorder (NMOSD) and are AQP4-IgG positive, with a first-attack episode;
* Male or female,age \>=18 and \<=65 years old;
* EDSS score ≤ 7.5;
* Female subjects of childbearing potential must have a negative pregnancy test result during the screening period and must use effective contraception throughout the study period;
* Voluntarily sign the informed consent form.
Exclusion Criteria:
* Laboratory abnormalities include: (white blood cell count \< 3×10⁹/L), (neutrophils \< 1.5×10⁹/L), (hemoglobin \< 85 g/L), (platelet count \< 80×10⁹/L), (serum creatinine \> 1.5×ULN), (total bilirubin \> 1.5×ULN), (AST (GOT) \> 3×ULN), (ALT (GPT) \> 3×ULN), (alkaline phosphatase \> 2×ULN).
* Patients currently suffering from active hepatitis or with a history of severe liver disease are ineligible. Based on the following serological test results for HBsAg, anti-HBc antibodies, and anti-HBs antibodies, there is evidence of hepatitis B virus (HBV) infection: Patients with positive HBsAg should be excluded. For patients with negative HBsAg but positive anti-HBc antibodies, regardless of whether anti-HBs antibodies are positive or negative, HBV-DNA testing is required to determine their status: If HBV-DNA is positive, the patient should be excluded; if HBV-DNA is negative, the patient may be eligible for the trial.
* Patients with other chronic active immune system diseases, or those with stable conditions but requiring glucocorticoid therapy, are excluded, except for neuromyelitis optica spectrum disorder (NMOSD). Examples include rheumatoid arthritis, scleroderma, Sjögren's syndrome, ulcerative colitis, AIDS, genetic immunodeficiency, or drug-induced immunodeficiency. Patients with only positive autoantibodies but without clinical manifestations may be eligible for the trial.
* Pregnant women, breastfeeding women, and patients who plan to conceive during the trial period.
* Allergic reactions: Patients with a history of allergies to contrast agents administered via the parenteral route or to human-derived biological products.
* Patients who received a live vaccine, except for the herpes zoster vaccine, within 28 days prior to randomization.
* Patients who have used rituximab or other monoclonal antibodies within 6 months prior to randomization
* Patients who have received intravenous immunoglobulin (IVIG) within 28 days prior to randomization.
* Patients who have undergone hematopoietic stem cell transplantation or lymphocyte irradiation before randomization.
* Patients who have used immunosuppressive agents such as azathioprine (Azathioprine, AZA, half-life t1/2 = 6 hrs), mycophenolate mofetil (Mycophenolate Mofetil, t1/2 = 16 hrs), leflunomide (Leflunomide, LEF, t1/2 = 14.7 hrs), tacrolimus (Tacrolimus, t1/2 = 43 hrs), teriflunomide (Teriflunomide, t1/2 = 18 days), cyclosporine (Cyclosporin, CsA, t1/2 = 27 hrs), methotrexate (Methotrexate, MTX, t1/2 = 14 hrs), mitoxantrone (Mitoxantrone, NVT, t1/2 = 37 hrs), and cyclophosphamide (Cyclophosphamide, CTX, t1/2 = 6 hrs) before randomization are excluded. Except for leflunomide and teriflunomide, patients can be enrolled if the washout period exceeds five half-lives. For leflunomide and teriflunomide, patients need to undergo cholestyramine washout as follows: take 8 grams of cholestyramine orally three times daily for 11 days. If the 8-gram dose is not tolerated, it can be changed to 4 grams per dose, with the same frequency and duration.
* Patients who have received any investigational drug within 28 days or five half-lives of the trial drug (whichever is shorter) before randomization.
* Patients with symptoms of severe mental illness who are clinically unable to co-operate;
* Patients with malignant tumours.
* Patients who have experienced any of the following events within 12 weeks prior to randomization: myocardial infarction, unstable ischemic heart disease, stroke, or New York Heart Association (NYHA) Class IV heart failure.
* Patients with herpes zoster infection, positive for HCV antibodies, or positive for HIV antibodies during the screening period.
* Patients who are unable to undergo magnetic resonance imaging (MRI) during the trial period.
* Patients whom the investigator deems unsuitable for participation in the trial.