We reported a 67-year-old man with myelodysplastic syndrome who developed carbapenem-resistant Acinetobacter baumannii (CRAB)-induced severe pneumonia and sepsis after allogeneic hematopoietic stem cell transplantation. Post-transplantation, he presented with fever, hypoxemia and productive yellow sputum; chest CT showed bilateral diffuse interstitial inflammation with areas of consolidation. Repeated sputum cultures and blood metagenomic next-generation sequencing confirmed CRAB infection. Initial multidrug regimens - including polymyxin B, meropenem and eravacycline - failed to achieve clinical improvement. A Sulbactam-Durlobactam (SUL-DUR)-based combination regimen was then introduced, along with immunomodulatory therapy and airway management. Inflammatory markers (CRP and PCT) decreased rapidly, pathogens were eradicated, and the patient was successfully weaned from mechanical ventilation and transferred to the general ward. This case suggested that SUL-DUR-based therapy was both effective and well-tolerated for severe CRAB infections during immune reconstitution, and offered a promising therapeutic option for complex post-transplant infections.