Inclusion Criteria:  Diagnosed as hematopoietic malignancy; Achieved complete remission since the last chemotherapy; Age 10-70 years； Be willing to receive allo-HSCT, with HLA matched related or HLA matched unrelated, or HLA mismatched related donor.  Exclusion Criteria:  Active infections, severe organ damage (cardiac, renal and/or hepatic dysfunction greater than grade 2 according to the Common Terminology Criteria for Adverse Events V5.0), or any other conditions that make patients ineligible for allo-HSCT; Allergic to acetylcysteine or decitabine.