Efficacy and Safety Evaluation of BCMA-UCART

Inclusion Criteria: * Have the capacity to give informed consent; * Confirmed diagnosis of active MM as defined by NCCN and IMWG criteria; * Have a diagnosis of BCMA+ multiple myeloma (MM), (≥ 5% BCMA+ in CD138+ plasma cells by flow cytometry obtained within 45 days of study enrollment); * Refractory and relapsed MM patients after \> 2 cycles of induction therapy,or,have relapsed or treatment refractory disease following autologous stem cell transplant (ASCT); * ECOG score=0-2. * Subjects according with any of the following options: * Age≥50; * Failure with separation of T cells during autologous CART processing; or, * Failure with expansion of autologous CART; or, * The proportion of T cells in PBMC \<10%; or, * Won't benefit from autologous CART therapy because of disease progress. Exclusion Criteria: * Pregnant or nursing women; Women of reproductive potential must have a negative serum pregnancy test performed within 48 hours of starting conditioning chemotherapy * Active infection, HIV infection, syphilis serology reaction positive; * Active hepatitis B, hepatitis C at the time of screening * Significant hepatic dysfunction as following, SGOT(serum glutamic-oxaloacetic transaminase)\> 5 x upper limit of normal; bilirubin \> 3.0 mg/dL; * Lymphotoxic chemotherapeutic agents within 2 weeks of leukapheresis * serious mental disorder; * With severe cardiac, liver, renal insufficiency, diabetes and other diseases; * Participate in other clinical research in the past three months; previously treatment with any gene therapy products * Contraindication to cyclophosphamide or fludarabine chemotherapy