Acute lymphoblastic leukemia occurs mostly in adolescents and is the malignancy with the highest incidence and mortality rate in people under 35 years of age, with acute B-lymphocytic leukemia being the most common. Although chemotherapy has been effective in childhood acute lymphoblastic leukemia, the prognosis for adults and children with relapsed or refractory acute B-lymphocytic leukemia remains poor, and even with salvage hematopoietic stem cell transplantation, most patients achieve only short-term disease control, with an average survival of usually less than one year. In the case of relapse after allogeneic HSCT or unconditionally treated with transplantation, these patients are basically in a hopeless situation. One of the most important recent innovations in biomedicine is chimeric antigen receptor T-cell therapy (CAR-T), which biologically modifies immune T cells in vitro to recognize antigens on the surface of cancer cells for targeted killing of cancer cells. The efficacy of CAR-T-CD19 in treating relapsed or refractory acute B-lymphocytic leukemia is most clear from the results of clinical trials to date, with an incredible Phase 2 clinical trial involving 59 pediatric or young adult patients with relapsed or refractory acute lymphoblastic leukemia reported at the recently concluded 57th Annual Meeting of the American Society of Hematology (ASH) in 2015 Good results: 93% complete response rate (55/59) and 1-year survival rate of 79%, with 55% of patients maintaining complete remission for more than 12 months. This novel therapy offers a ray of hope and hope for patients with relapsed or refractory acute B-lymphocytic leukemia. In order to bring this new technology to the benefit of Chinese patients as soon as possible, the Department of Hematology has collaborated with Anhui Beida Wei Ming Institute of Bioeconomics to develop CAR-T-CD19 cell therapy for acute B-lymphocytic leukemia, and the first 24 patients with relapsed or refractory acute B-lymphocytic leukemia are scheduled to enter clinical trials. Patients with relapsed refractory acute B-lymphocytic leukemia (B-ALL) who have failed other conventional therapies and are confirmed positive for the leukemia cell antigen CD19 prior to treatment. Age 3 to 75 years, fair general condition, basically normal cardiac, hepatic and renal function, and no serious infections. Basically normal peripheral blood picture (i.e., leukocytes ≥ 4.0×109/L, hemoglobin > 100g/L, platelet count ≥ 50×109/L), peripheral blood cell index may be relaxed to leukocytes ≥ 2.0×109/L, hemoglobin > 60g/L, platelet count ≥ 30 after adequate notification of relevant risks and obtaining understanding and consent in patients with rapid disease progression and special severe disease x109/L.