A Multi-center, Non-randomized, Open-label Phase II Clinical Study on the Treatment of Newly Diagnosed Advanced Hodgkin's Lymphoma With PD-1 Antibody (Tislelizumab) Combined With AVD Regimen (Doxorubicin, Vindesine, Dacarbazine) Under the Guidance of PET/CT

Inclusion Criteria: 1. Patients with newly diagnosed classical Hodgkin lymphoma (HL) confirmed by histopathology; 2. Stage III-IV, or Stage IIB patients with at least one high-risk factor (NCCN standard) 3. Patients not suitable for receiving radiotherapy subsequently 4. Patients with at least one assessable lesion (according to Lugano 2014 standard); 5. Age 18 or above (including 18), no gender requirement; 6. ECOG PS score of 0-1 points; 7. Expected survival time ≥ 3 months; 8. Hematopoietic function: absolute neutrophil count ≥ 1.5×109/L, platelets ≥ 90×109/L, hemoglobin ≥ 90g/L; liver function: for patients with non-hepatitis B, total bilirubin, ALT and AST \<1.5×ULN (upper limit of normal); patients with hepatitis B need to take effective antiviral drugs, and HBV-DNA copy \<2000 IU/ml and ALT\<2×ULN; renal function: creatinine \<1.5×ULN and creatinine clearance rate ≥50ml/min; 9. With normal main indicators of cardio-pulmonary function, and no obvious contraindication to chemotherapy; 10. Not received any anti-tumor therapy such as radiotherapy, chemotherapy, targeted therapy, cellular immunotherapy or hematopoietic stem cell transplantation before enrollment; 11. Voluntarily signing an informed consent form before trial screening. Exclusion Criteria: 1. Nodular lymphocyte predominant HL; 2. Patients received any form of anti-tumor therapy in the past; 3. Patients planning to receive radiotherapy or autologous stem cell transplantation; 4. With involvement of central nervous system (meninges or brain parenchyma); 5. Pregnant and lactating women and child-bearing patients who are unwilling to take contraceptive measures; 6. Patients with history of other tumors, except for cured cervical cancer orskin basal cell carcinoma; patients who have received organ transplantation; 7. Patients who have received symptomatic treatment of myelosuppressive toxicity within 7 days before enrollment; 8. Patients who have used any immunosuppressive drugs within 4 weeks before the first-dose treatment, 9. Patients with known active interstitial pneumonia; 10. Abnormal liver function (total bilirubin\>1.5×ULN, ALT/AST\>2.5×ULN or ALT/AST\>5×ULN for patients with liver invasion), abnormal renal function (serum creatinine\>1.5×ULN), abnormal electrolyte metabolism; 11. Peripheral neuropathy ≥ Grade 2; 12. Patients with a history of prolonged QT interval which is of clinical significance (male\> 450ms, female\> 470ms), ventricular tachycardia (VT), atrial fibrillation (AF), heart block, myocardial infarction (MI) within 1 year, congestive heart failure (CHF), patients with symptomatic coronary heart disease requiring drug therapy; 13. Patients with the end-diastolic width of fluid sonolucent area in pericardial cavity ≥10mm by cardiac B-ultrasonography; 14. Mentally disturbed/patients unable to give informed consent; 15. Patients who affect the evaluation of test results due to drug abuse or long-term alcohol abuse; 16. Participating in another interventional clinical study at the same time; Patients not suitable to participate in this trial by the judgment of investigators.