Intensified conditioning regimen allo-HSCT is based on a hypothesis of that intensifying condition with less-used drugs could overcome resistance,reduce tumor burden, and most importantly, spare enough time for slow-growing GVL effect following immune reconstitution to finally get rid of MRD and control the disease. Our previous trial of HDE-ALL-2011 (NCT01457040) have confirmed the role of intensified conditioning allo-HSCT in adult ALL, resulting in significantly improved OS and EFS in comparison with previous standard TBI/CY2 conditioning regimen(data not yet published). But at the same time, FA-TBI/CY2-VP16 conditioning regimen was associated with high transplantation-related mortality (TRM), which might be attributed to excessive suppression on both bone marrow and immune. TT-ALL-HIE-2013, substituting FA with idarubicin, is aimed at maintaining anti-tumor effect with less cross-resistance and immune suppression and reducing TRM.