This is a single arm, open-label, single center study to evaluate the safety and efficacy of BCMA/CD19 CAR-T cells in patients with BCMA+，CD19+ relapsed or refractory multiple myeloma.

CD19 has been extensively evaluated as a therapeutic target for relapsed or refractory multiple myeloma by chimeric antigen receptor T cell therapy,this is a single arm, open-label, single center study to preliminary explore the safety, tolerability and cellular pharmacokinetics of Anti-BCMA and Anti-CD19 CAR-T cells in the treatment of relapsed or refractory multiple myeloma.

Inclusion Criteria:

1. Male or female aged 18-70 years old
2. Estimated Survival time > 12 weeks
3. Relapsed and refractory multiple myeloma were confirmed by physical examination, pathological examination, laboratory examination and imaging
4. Chemotherapy failure or recurrent multiple myeloma
5. Glutamic-pyruvic transaminase, glutamic oxalacetic transaminase< 3 fold of normal level
6. Bilirubin<2.0mg/dl
7. Karnofsky Performance Status>50% at the time of screening
8. Adequate pulmonary, renal, hepatic, and cardiac function
9. Fail in autologous haemopoietic stem cell transplantation
10. Not suitable for stem cell transplantation conditions or abandoned due to conditions
11. Free of leukocytes removal contraindications
12. Voluntarily join CAR-T clinical trial ,Understand and sign written informed consent

Exclusion Criteria:

1. The patient is a pregnant or breastfeeding woman, or is a woman with a pregnancy plan within six months
2. Patients have infectious diseases (such as HIV, active tuberculosis, etc.)
3. The patient is an active hepatitis B or hepatitis C infection
4. Feasibility assessment proves that the efficiency of transduction of lymphocyte is below 10% or the lymphocyte cannot be propagated
5. Abnormal vital signs
6. Subjects with mental or psychological illness who cannot be combined with treatment and efficacy evaluation.
7. Highly allergic constitution or history of severe allergies, especially allergy to interleukin-2
8. General infection or local severe infection, or other infection that is not controlled
9. Dysfunction in lung, heart, kidney and brain
10. Severe autoimmune diseases
11. Other symptoms that are not applicable for CAR-T