Inclusion Criteria:
* Volunteer to participate in the clinical trial; participants fully understand and are informed of this trial and sign the informed consent form; Willing to follow and able to complete all trial procedures;
* Age 18 \~ 75 years (inclusive);
* Histologically or cytologically confirmed large B-cell lymphoma (LBCL), including diffuse large B-cell lymphoma unspecified (DLBCL, NOS), primary mediastinal large B-cell lymphoma (PMBCL), high-grade B-cell lymphoma(HGBL), large B-cell lymphoma (FLBL) transformed by follicular lymphoma (FL)/Grade 3b FL;
* Has received at least 2 prior lines of standard systemic therapy and has relapsed after adequate treatment or meets refractory criteria.
* If the participant has received prior CD19-targeted therapy, the tumor tissue should be re-collected at least 4 weeks after the last dose for CD19 and CD20 detection to confirm that the expression of CD19 or CD20 is positive;
* Presence of at least one measurable lesion according to the Lugano 2014 criteria (a previously irradiated lesion is not to be considered measurable or non-measurable unless it has unequivocal progression or tumor activity after completion of radiation therapy), at least one of the following conditions is required:As measured by computed tomography (CT) or magnetic resonance imaging (MRI): nodal lesions \> 1.5 cm in long diameter or extranodal lesions \> 1.0 cm in long diameter;
* Estimated survival \> 12 weeks;
* Eastern Cooperative Oncology Group (ECOG) performance status 0-1;
* Participants should meet the following test results (there should be no ongoing supportive care):
* Female participants of child-bearing potential must have a negative pregnancy test at screening and before receiving clearing therapy, be willing to use a highly effective and reliable method of contraception within 1 year after receiving trial therapy, and absolutely prohibit egg donation within 1 year after receiving trial therapy infusion during the trial; A male participant, if sexually active with a female of childbearing potential, is willing to use a highly effective and reliable method of contraception for 1 year after receiving trial treatment. All male participants absolutely refrain from donating sperm for 1 year after receiving the trial treatment infusion during the trial.
Exclusion Criteria:
* Pregnant or lactating women;
* Presence of HIV, syphilis infection, active hepatitis B virus infection, active hepatitis C virus infection, DNA positive (whole blood or plasma), cytomegalovirus (CMV) DNA positive;
* Any uncontrollable active infection;
* The toxic side effects caused by the participant's previous treatment have not recovered to the standard for adverse events (CTCAE v6.0) ≤ 1, except for hair loss and other tolerable events determined by the researcher;
* Individuals with known symptomatic central nervous system (CNS) disorders or suspected involvement of CNS lymphoma;
* Patients with lymphoma involving the small intestine or the muscular layers of the stomach and colon;
* Received autologous hematopoietic stem cell transplantation within 12 weeks prior to signing the informed consent form;
* Participants have received allogeneic hematopoietic stem cell transplantation in the past;
* Participants who have previously received targeted CD19 CAR-T therapy and have tested positive for anti drug antibodies (ADA) within the last 4 weeks prior to signing the main informed consent form;
* Vaccination with live or attenuated vaccines within 4 weeks prior to signing the informed consent form;
* Select patients with any of the following heart diseases within the first 6 months of screening:
* Blood oxygen saturation\<92% (in non oxygen state), or suffering from other serious lung diseases that the researcher has determined may endanger the patient's life by participating in the study;
* Within the past 2 years, there has been a second primary malignant tumor that requires treatment or has not fully resolved;
* Participants with a history of organ transplantation or waiting for organ transplantation;
* Having undergone major surgical procedures within 2 weeks prior to signing the informed consent form, or planning to undergo major surgical procedures during the trial period or within 4 weeks after receiving the trial treatment (excluding local anesthesia surgeries such as cataracts);
* The researchers assessed that participants were unable or unwilling to comply with the requirements of the protocol, or had other reasons that made them unsuitable to participate in this clinical trial.
