Inclusion Criteria:  EBV-HLH according to the HLH-04 diagnostic criteria. After allo-HCT, have achieved engraftment and reconstitute of hematopoiesis. have achieved full donor chimerism. Withdraw immunosuppressive agent, chimeric rate was 80%-95% Age >18 years old, gender is not limited. no graft-versus-host disease was observed. No secondary graft failure (ANC <0.5*10^9/l,PLT <10*10^9/l) Before the start of the study, aminopherase (ALT/AST) and total bilirubin were normal. Serum creatinine ≤ 1.5 times the upper limit of Normal (ULN); No thyroid dysfunction. The left ventricular ejection fraction (LVEF) was normal. Informed consent.  Exclusion Criteria:  Allergic to the test drug ingredients or to a more severe allergic constitution. Chimeric rate continue to decline after 2 weeks of toripalimab Injection used. Serious immunoreaction: myocardial damage, hepatitis, pneumonia. Central nervous system symptoms. Serious mental illness. Active bleeding of the internal organs Uncontrollable infection； Pancreatitis history. Patients unable to comply during the trial and/or follow-up phase; Participate in other clinical research at the same time.