Inclusion Criteria:  Pathological immunohistochemistry or flow cytometry confirmed that R/R PTCL with measurable (diameter greater than 1.5cm) lesions meets any of the following conditions: 1> After 4 courses of standard first-line therapy or 2 courses of more than two-line therapy, the lesions were reduced by <50%; 2> PTCL with disease progression after first-line or induction therapy; 3> After hematopoietic stem cell transplantation, new lesions appear or the size of previously affected lesions increased by more than 50%. Age ≥ 18 years. ECOG≤2分. The main organ functions need to meet the following conditions:Hemogram needs to meet HB ≥70*1012/L，PLT≥50*109/L，NE≥1*109/L；LVEF≥50%;CR≤132umol/l or CCr≥60 ml/min;ALT and AST≤2 times normal range；Lung function≤Level 1;dyspnea(CTCAE v5.0),and blood oxygen saturation without oxygen absorption> 91%. Subjects of child-bearing or child-fathering potential must be willing to practice birth control from the time of enrollment on this study until the follow-up one year period of the study. Estimated survival time ≥3 months. Voluntary signing of informed consent.  Exclusion Criteria:  Accepted major surgery within 4 weeks before treatment. Prior malignancy (other than Relapsed/Refractory Peripheral T-cell Lymphoma), except for cured malignant tumors with no active lesions for 3 years;Adequate treatment of inactive lesions in non-melanoma skin cancer,malignant tonsilloma or carcinoma in situ; Patients who have previously received failed allogeneic hematopoietic stem cell transplantation. Have stroke or intracranial hemorrhage within 3 months. Evidence of complications or medical conditions, including but not limited, that may interfere the conduct of the study or place the patient at serious risk:significant cardiovascular disease(class 3 or 4 cardiac disease as defined by the New York Heart Association Functional Classification、myocardial infarction within 6 months of screening、uncontrolled or symptomatic arrhythmias) and/or significant lung disease. HIV infection and/or active hepatitis B or active hepatitis C. Uncontrolled systemic infection. Pregnant or breasting-feeding women. According to the researchers' judgment, any life-threatening disease, medical condition or organ system dysfunction which can endanger the patient's safety and Interfer with the absorption or metabolism of anti-PD-1 monoclonal antibody plus Lenalidomide and Azacitidine,may put the results of a study at unnecessary risk.