Objective To explore the dietary management experiences of caregivers of pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), and to provide references for developing targeted nursing interventions. Methods A descriptive qualitative study was conducted using the Health Belief Model as the theoretical framework. Face-to-face, semi-structured in-depth interviews were carried out with 17 caregivers of pediatric patients undergoing allo-HSCT. Data were analyzed using directed content analysis. Results Five themes and fifteen subthemes were identified: perceptions of health risks associated with dietary changes (weight loss, inadequate nutritional intake, fatigue, emotional resistance); recognition of the positive effects of proper dietary management (improved appetite and acceptance, better health outcomes, enhanced sense of responsibility); barriers to dietary management (conflicting dietary guidance, difficulties in meal preparation, poor patient adherence); agentic characteristics of dietary management behaviors (dual nature of emotional coping, differences in behavior patterns); and demand for optimized dietary management guidance (visualized dietary guidance, stage-specific dietary guidance, information platform-based dietary guidance). Conclusion Caregivers of pediatric patients undergoing allo-HSCT face significant challenges and unmet needs in dietary management. Healthcare professionals should pay close attention to changes in patients′ eating behaviors, optimize intervention strategies, strengthen caregivers′ self-efficacy, and improve their capacity for effective dietary management.