This is an open label, single arm, phase I/II for patients with r/r Non-Hodgkin's Lymphoma

. The purpose is to evaluate the safety and efficacy of the combination with Azacytidine, Bendamustine and Piamprizumab

Inclusion Criteria:

1. Age ≥18 and ≤80 years
2. Performance status (ECOG) between 0 and 3.
3. Histologically confirmed B-cell non-Hodgkin lymphoma (NHL), including the following types defined by WHO 2016.
4. Refractory disease or relapsed after treatment with ≥2 lines of chemotherapy and either having failed autologous HSCT or being ineligible for or not consenting to autologous HSCT; or not suitable for CAR T treatment or resistance, progression or relapse after CAR T treatment; or CAR T pre-culturing losers can also be enrolled.
5. Adequate organ function.
6. An adequate bone marrow reserve.
7. Measurable or assessable disease according to the"IWG Response Criteria for Malignant Lymphoma"(Cheson 2014). Patients in complete remission (CR) with no evidence of disease were not eligible.
8. Informed consent/assent requiring that all patients have the ability to understand and the willingness to provide written informed consent.
9. Life expectancy > 12 weeks.
10. Patients with definite involvement of the gastrointestinal tract, and patients with central nervous system (CNS) by PETCT and MRI involvement were allowed to enrolled in this clinical study.

Exclusion Criteria:

1. Pregnant or lactating women.
2. Uncontrolled medical disorders, active bacterial, viral infection or treponema pallidum infection and so on.
3. Requirement for urgent therapy due to tumor mass effects such as respiratory obstruction or blood vessel compression.
4. Current or expected need for systemic corticosteroid therapy.
5. Any organ failure.
6. Patients with a second tumor requiring therapy or intervention.
7. Subjects considered unlikely to complete all protocol-required study visits or procedures, including follow-up visits, or comply with the study requirements for participation according to the investigator's judgement.
8. Prior organ allograft.
9. Subjects who are compulsorily detained for treatment of either a psychiatric or physical (eg, infectious disease) illness.