This study evaluates the effectiveness and safety of a new conditioning regimen called VABu before stem cell transplantation in patients with acute myeloid leukemia (AML) who are in their first complete remission (CR1), classified as non-high-risk per ELN 2022 guidelines, but have poor physical condition (ECOG performance status ≥ 2) or high comorbidity burden (HCT-CI ≥ 2). VABu combines venetoclax, azacitidine (or decitabine as an alternative), and busulfan. This is a single-arm, prospective study with 42 participants. All participants will receive the VABu regimen followed by stem cell transplantation. The primary outcome measure is 2-year overall survival (OS). Secondary outcomes include 2-year relapse-free survival (RFS), transplant-related mortality (TRM), engraftment failure rate, bloodstream infection (BSI), and 2-year all-cause mortality and non-relapse mortality (NRM). The study is conducted at the First Affiliated Hospital of Soochow University.