Anti-BCMA CAR-NK Cell Therapy for the Relapsed or Refractory Multiple Myeloma

Inclusion Criteria: 1. Signed written informed consent; 2. According to the international standard for multiple myeloma，have information on medical examination proving the diagnosis of multiple myeloma. 3. Received at least 2 prior lines of treatment, including proteasome inhibitor and immunomodulator, no efficacy more than PD; disease progression or relapsed after disease remission and refractory or no remission after treated in the last time. 4. Measurable disease at screening as defined by any of the following: Serum monoclonal paraprotein (M-protein) level ≥1.0 g/dL or urine M-protein level veing as defined ；or light chain MM without measurable disease in the serum or the urine；serum immunoglobulin free light chain isease dL and abnormal serum immunoglobulin kappa/lambda free light chain ratio ； 5. ECOG Scores: 0\~2（See Annex 3），the estimated survival time was more than 3 months; 6. During the screening period, the clinical laboratory values met the following criteria： Hemoglobins70g/L (did not receive red blood cell transfusion ≤7 days prior to laboratory tests，recombinant human erythropoietin is allowed); Platelet count \>50×10\^9/L (did not receive blood transfusion ≤7 days prior to laboratory tests); Neutrophil absolute count oietin is (did not receive supportive treatment lowed); Platelet count \>50×10\^9/L，allowed to use over growth factor support); ALT and AST ≤3×ULN；Total bilirubin ≤2.0× UNL；Creatinine clearance×40mL/min；corrected serum calcium L/minctordL (3.1 mmol/L), or free calcium ion or freedL(L( ommol/L); Prothrombin time and activated partial thromboplastin time ≤1.5×ULN. 7. The urine pregnancy test of female subjects of childbearing age should be negative and not in lactation; 8. Females of childbearing potential and males must use efficient contraception（form signing the ICF to the end of the trial） Exclusion Criteria: 1. Have received CAR-NK therapy； 2. Have a history of allergy to any component of cell products; 3. Previous history of other malignancy; 4. Any unstable cardiovascular disease happened the informed consent form by themselves or their legal guardian;boratory tests); be infused using the "3 + 3" dos grade), severe arrhythmia that require drug interference, cardiac angioplasty/coronary stent implantation/cardiac bypass surgery ≤6 months prior to enrollment; 5. Have received allogeneic hematopoietic stem cell transplantation in 3 months for the treatment of multiple myeloma; 6. who has suffered from brain injury, consciousness disorder, epilepsy, more serious cerebral ischemia or cerebral hemorrhage disease; 7. There were live vaccinations within 4 weeks before admission; 8. Active hepatitis (positive for HBVDNA or HCVRNA), syphilis and other acquired and congenital immunodeficiency diseases, including but not limited to those with HIV infection; 9. Oxygen is needed to maintain adequate oxygen saturation; 10. Contraindications for fludarabine or cyclophosphamide treatment. 11. There was uncontrolled active infection;Patients with autoimmune diseases, immunodeficiency or other diseases requiring immunosuppressive （excluding glucocorticoid）therapy; 12. Pregnant or breasting-feeding women; 13. Subjects had a history of alcohol, drug or mental illness; 14. Any other condition that researcher think it is inappropriate for the subject to anticipate the trial.