After allogeneic hematopoietic stem cell transplantation (allo-HSCT), recipients are immunocompromised and at increased risk of complications, including cytomegalovirus (CMV) infection. International clinical guidelines for the management of CMV infection post-allo-HSCT recommend three main strategies: minimizing infection risk, prevention, and preemptive therapy. However, traditional antiviral agents have not been approved for CMV prophylaxis in allo-HSCT recipients and are associated with significant adverse effects and the development of resistance, leaving the CMV prevention needs of this patient population unmet. Recent studies have demonstrated that letermovir prevents potent and highly specific antiviral activity against CMV, and it has been approved for CMV prophylaxis within the first 100 days post-allo-HSCT. Furthermore, evidence suggests that extending letermovir administration up to 28 weeks further reduces the risk of CMV infection in the later post-transplant period without increasing drug-related mortality. In China, the post-allo-HSCT CMV prevention strategy faces challenges such as limited treatment options, unclear guideline recommendations, non-standardized drug usage in certain medical institutions, and insufficient monitoring. This study aims to provide robust, evidence-based support for the use of letermovir in high-risk CMV reactivation among adult allo-HSCT recipients, thereby broadening clinical treatment choices.