Inclusion Criteria:  1) Willing and able to provide signed and dated informed consent prior to any study-related procedures and willing and able to comply with all study procedures;  2) Male or female ≥ 18 years;  3) Patient has a history of multiple myeloma with relapsed and refractory disease, and must:  Relapsed after an autologous stem cell transplant (ASCT), or not suitable for ASCT;  Must have received at least 2 prior multiple myeloma treatment regimens (not including autologous stem cell transplant) including a proteasome inhibitor, an immunomodulatory agent;  4) ECOG of 0-2;  5) Patients must have measurable disease, including at least one of the criteria below:  M-protein ≥ 0.5 g/dL by SPEP/immunofixation or ≥ 200 mg/24 hours urine collection by UPEP or  Serum free light chain (FLC) levels > 100 mg/L (milligrams/liter involved light chain) and an abnormal kappa/lambda (κ/λ) ratio in patients without detectable serum or urine M-protein;  6) Adequate hepatic function as evidenced by meeting all the following requirements:  Blood routine: absolute neutrophil count (ANC) ≥ 1.0×109/L, hemoglobin (Hb) ≥70g/L, Platelet ≥ 50×109/L; Liver function: total bilirubin ≤ 1.5 × upper limit of normal (ULN), alanine aminotransferase (ALT) ≤ 2.5 × ULN, Aspartate aminotransferase (AST) ≤ 2.5 × ULN;  Renal function: calculated creatinine clearance (CrCL) ≥ 30 mL/min (Cockroft-Gault Equation).  7) Recovery to Grade 0-1 from adverse events related to prior anticancer therapy except alopecia, ≤ Grade 2 sensory neuropathy, lymphopenia, and endocrinopathies controlled with hormone replacement therapy.  Exclusion Criteria:  1) Patient has primary light chain amyloidosis or plasma cell leukemia;  2) Patient has symptomatic central nervous system involvement of multiple myeloma;  3) Received systemic anti-myeloma therapy within 2 weeks, or received plasma exchange within 4 weeks;  4) Received any experimental drugs within 4 weeks or 5 half-lives (whichever is shorter);  5) Patient has received ≥ 40 mg/day dexamethasone equivalent within 7 days before starting F182112. Short term use of corticosteroids at doses equivalent to > 10 mg/d of prednisone；  6) Received any monoclonal antibody therapy within 30 days;  7) Prior treatment with any B cell maturation antigen (BCMA) targeted therapy;  8) Patient had a prior allogeneic stem cell transplant or had a prior autologous stem cell transplant ≤ 3 months prior to starting F182112;  9) Live virus vaccine within 30 days prior to study entry;  10) Major surgery within 4 weeks prior to study entry;  11) Concurrent malignancy within 3 years prior to entry other than adequately treated cervical carcinoma-in-situ, localized squamous cell cancer of the skin, basal cell carcinoma, prostate cancer under active surveillance, prostate cancer that has undergone definitive treatment, ductal carcinoma in situ of the breast, or ≤ T1 urothelial carcinoma;  12) Patients with active mucosa or visceral bleeding;  13) Severe cardiovascular disease, including CVA, TIA, myocardial infarction, or unstable angina within 6 months of study entry; NYHA class III or IV heart failure within 6 months of study entry; Uncontrolled arrhythmia within 6 months of study entry. Patients with a rate-controlled arrhythmia may be eligible for study entry at the discretion of the Medical Monitor;  14) Active infection requiring antibiotic, antiviral or antifungul therapy;  15) Active viral hepatitis;  16) Has a history of immunodeficiency, include HIV infection;  17) Treponema pallidum infection;  18) Received any experimental drugs or anti-tumor drugs within 2 weeks;  19) Subject has any condition that confounds the ability to interpret data from the study;  20) Females and males must practice true abstinence or agree to contraceptive methods throughout the study, and 6 months after the last giving F182112;  21) Any condition that the investigator or primary physician believes may not be appropriate for participating the study.