• Patients that can understand and voluntarily sign an informed consent document prior to the study;

• Male and female subjects ≥ 18 years and ≤ 65 years of age at the time of signing the informed consent document.

• Fulfilling the ICBD (International Conference on Behcet's Disease) criteria(2013);

• Presented with active mucosal lesions: Subjects must have at least 1 oral ulcer within 4 weeks after the screening visit and at least 2 oral ulcers on the day of enrollment; subjects may be with or without genital ulcers and (or) skin lesions.

• Refractory mucosal lesions: Subjects must experience at least 2 relapses of oral ulcers during 3 consecutive months of conventional treatment with corticosteroids and(or) immunosuppressants.

• Without major organ involvement, including active gastrointestinal, ocular, nervous system, and major vessel involvement; previous major organ involvement is allowed if it occurred at least 1 year prior to the screening visit and is not active at the time of enrollment.; subjects with arthritis are permitted.