Inclusion Criteria:
1\. Age range: 18-70 years old, gender not restricted. 2. Patients diagnosed with NK/T cell lymphoma through histopathology or flow cytometry, 1) with stage III/IV patients receiving first-line or salvage treatment and achieving remission, 2) stage II patients with relapsed/refractory disease after salvage treatment achieving remission, 3) patients with NK cell lymphoma/leukemia receiving first-line or salvage treatment and achieving remission, 4) patients with relapsed/refractory disease. 3. Patients must have a suitable hematopoietic stem cell donor. 1) The related donor must have at least 5/10 HLA-A, -B, -C, -DQB1, and -DRB1 matching. 2) The unrelated donor must have at least 8/10 HLA-A, -B, -C, -DQB1, and -DRB1 matching. 4. HCT-specific comorbidity index score (HCT-CI) \<= 2. 5. ECOG: 0-2 points. 6. Liver and kidney functions, as well as heart and lung functions, must meet the following requirements: 1) Serum creatinine \<= 1.5 × ULN; 2) Cardiac function: Ejection fraction \>= 50%; 3) Basal oxygen saturation \> 92%; 4) Total bilirubin \<= 1.5 × ULN; ALT and AST \<= 2.0 × ULN; 5) Pulmonary function: DLCO (hemoglobin corrected) \>= 40% and FEV1 \>= 50%. 7. Patients must be capable of understanding and willing to participate in this study, and sign the informed consent form.
Exclusion Criteria:
1\. Patients allergic to stietap, cyclophosphamide or busulfan or its components. 2. Any unstable systemic diseases: including but not limited to unstable angina pectoris, cerebrovascular accident or transient cerebral ischemia (within 3 months before screening), myocardial infarction (within 3 months before screening), congestive heart failure (NYHA classification ≥ III), severe arrhythmia requiring drug treatment, liver, kidney or metabolic diseases;patients with pulmonary hypertension. 3. Active and uncontrolled infections: hemodynamic instability related to infection, or new symptoms or signs of infection worsening, or new infection lesions found on imaging, persistent fever without exclusion of infection without symptoms or signs; 4. Grade 2 or higher epilepsy, paralysis, aphasia, new cerebral infarction, severe brain trauma, dementia, Parkinson's disease, schizophrenia 5. HIV-infected patients; 6. Patients with active hepatitis B (HBV) or active hepatitis C (HCV) requiring antiviral treatment; 2.patients with a risk of HBV activation, referring to those with positive hepatitis B surface antigen or core antibody but not receiving anti-hepatitis virus treatment; 7. Pregnant or lactating women; 8. Male and female individuals with reproductive capacity who are unwilling to use contraceptive methods during treatment and within 12 months after treatment; 9. Patients whose study investigators assess have other inadvisable inclusion conditions.
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