• Age ≥ 18, upper limit 75, male or female;

• ECOG score 0-3;

• Histologically confirmed diffuse large B-cell lymphoma (DLBCL) \[diagnostic criteria according to WHO 2008\];

• CD19 positive (immunohistochemistry or flow cytometry).

• DLBCL refractory or relapse is defined as: complete remission is not achieved after 2-line treatment; let What disease progress occurs during treatment, or the disease stability time is equal to or less than 6 months; Or autologous hematopoietic stem Disease progression or recurrence within 12 months after cell transplantation;

• Previous treatment for patients with diffuse large B cell lymphoma must include rituximab (CD20 monoclonal antibody) and anthracyclines;

• At least one measurable lesion is required, and any lymph node lesion with a length greater than 1.5cm or extranodal lesion is required If any length diameter is greater than 1.0 cm, the lesions on PET-CT scan have uptake (SUV is larger than liver blood pool);

• Absolute value of peripheral blood neutrophils ≥ 1000/ μ l. Platelets ≥ 45000/ μ l

• Heart, liver and kidney functions: creatinine \< 1.5mg/dL; ALT/AST Less than 2.5 times of normal upper limit; Total bilirubin \< 1.5mg/dL; Cardiac ejection fraction (EF) ≥ 50%;

⁃ Have sufficient understanding and voluntarily sign the informed consent form;

⁃ People with fertility must be willing to use contraceptive methods;

⁃ According to the judgment of the researcher, the expected survival period is at least 4 months;

⁃ Willing to follow the visit schedule, administration plan, laboratory inspection and other test steps.