• Voluntarily sign a documented IRB-approved ICF prior to any screening procedure.

• No gender limitation, 14 years ≤ age ≤ 65 years.

• Intention to HSCT therapy.

• Meeting the diagnostic criteria of relapsed or refractory B-ALL. Relapsed B-ALL: Reappearance of blasts in the blood or bone marrow (\>5%) or in any extramedullary site after a CR. Refractory B-ALL: Failure to achieve CR or CRi at the end of induction therapy (General refers to a 4-week regimen or a Hyper-CVAD regimen); Subjects with Ph+ disease are eligible if they are intolerant to TKI therapy, or if they have relapsed/refractory disease despite treatment with at least 2 different TKIs.

• Life expectancy ≥ 8 weeks at the time of enrollment.

• Eastern Cooperative Oncology Group performance status score of 0 or 1.

• Adequate bone marrow, renal, hepatic, pulmonary and cardiac function:

‣ Adequate marrow function for lymphodepletion chemotherapy assessed by the investigator.

⁃ Creatinine clearance \> 30 mL/min according to the Cockcroft-Gault formula;

⁃ ALT and AST ≤ 5 × ULN (the upper limit of normal), total bilirubin ≤ 2×ULN. (Subjects with Gilbert syndrome or liver involvement may be included if their total bilirubin is ≤ 3 × ULN.)

⁃ Oxygen saturation (SaO2) ≥ 92% on room air.

⁃ Cardiac function：left ventricular ejection fraction (LVEF) ≥ 40% assessed by echocardiography.

• CD19-positive leukemia obtained from bone marrow or peripheral blood confirmed by flowcytometry or biopsy during screening.