• Age greater than or equal to the age of 18 and less than or equal to 65 patients, gender not limited;

• Met the 2015 international NMO diagnostic panel (IPND) criteria for NMOSD, And AQP4-IGG positive patients

• Screening before 2 times at least 2 years experience with clinical records of relapse，or experienced at least 1 clinically documented recurrence within 1 year prior to screening

• For subjects who had a relapse before screening, symptoms needed to be stable for at least 4 weeks before randomization

• Into the group of former dosage of corticosteroids under 30 mg and prednisone equivalent，and the trial drug must be used within a month after the withdrawal of hormones

• The score of EDSS 7 or less

• Has the fertility of men and women must agree during treatment and 6 months after the last dose of using effective birth control method;

• Agreed to participate in trials, and books to sign the informed consent