Background: The outcome of hematopoietic stem cell transplantation (HSCT) in children and adolescents with refractory or relapsed acute leukemia in nonremission is poor. However, It is uncertain whether an intensitive conditioning regimen can improve the outcomes or not . This retrospective analysis aimed to investigate the outcomes of HSCT with tumor-ablative conditioning regimen (TAC), the safety and efficiency of HSCT using TAC in nonremission acute leukemia . Procedure: Data from the Beijing Aerospace Central Hospital on 44 patients with nonremission acute leukemia (aged <18 years, with blasts 5-98% in bone marrow) who had undergone HSCT between January 2016 and December 2018 were evaluated. Results: Overall, 32 patients died. The median follow up was 1330 days in survival patients, and the 3-year OS and LFS were 27.3%( 95% CI, 14.2% to 40.4% ) and 28.9%（95% CI, 15.4% to 42.4%）. The cumulative incidence of relapse is 59.1% (95% CI, 44.6% to73.6) and non-relapse mortality (NRM) is 18.1%, 95 CI, 12.4%-23.8%). Multivariate analysis showed that relapse was an independent factor affecting OS (HR=4.308 (95% CI: 1.820-10.186,P=0.001) Conclusion: this 3-year retrospective analysis found that salvage HSCT with TAC is an alternative selection on nonremission leukemia, the TAC regimen is a safe and effective regimen. The relapse is still the main cause of death. A larger prospective study is needed to verify the promising study.