The purpose of this study is to evaluate the efficacy and safety of B007 in subjects with generalized myasthenia gravis.

Inclusion Criteria:

1. Sign informed consent form;
2. Subjects with generalized myasthenia gravis;
3. Serum AchR(Acetylcholine receptor)-Ab or MUSK-Ab was positive during screening;
4. MG-ADL ≥5 at screening and baseline;
5. Before randomization, subjects received at least one gMG stable dose of SoC, and maintain a stable dose throughout the test;
6. Subjects agree to use effective contraceptive methods for contraception from signing the informed consent form to 1 year after the last dose. Female subjects considered fertile by the investigator must have negative serum pregnancy tests before the first dose.

Exclusion Criteria:

1. Subjects with MGFA I and V type;
2. Subjects usingprescribed drugs;
3. Subjects with a prescribed disease or history of disease;
4. The subjects has prescribed examination abnormalities that are assessed as unsuitable for participation in the study by the investigator;
5. Known history of severe allergic reaction to humanized monoclonal antibodies, or known allergy to any component of B007;
6. Subjects who received live vaccine at the specified time before the first dose and are expected to receive the vaccine at the specified time after the last dose;
7. Subjects who have received major surgery or participated in other clinical trials within the prescribed time before screening;
8. Pregnant and lactating women;
9. Fertile female subjects do not agree to use effective contraception from signing the informed consent form to 1 years after the last dose.
10. Sexually active male subjects who do not intend to use an effective contraceptive method during the trial period or within1 years after the last dose, or male subjects who plan to donate sperm during the trial or within 1 year after the last dose;
11. A history of alcohol or drug abuse within the past 12 months;
12. Other conditions deemed unsuitable for participation in this study by the researchers.