Abstract: Objective: To explore the diet therapy care experience of children with Methylmalonic Acidemia (MMA), in order to provide reference and basis for promoting the management of children's diet therapy. Methods: Using the phenomenological research method and the purposeful sampling method, from September to December 2021, 16 caregivers of children with isolated MMA who were treated or revisited in a tertiary grade A hospital in Shandong province were selected for semi-structured interviews. The Nvivo 12 software was used to organize the interview data. Using the thematic analysis method to analyze and refine the themes. Results: A total of 5 themes and 14 sub-themes were extracted through inductive analysis, and the 5 themes were: children's self-restriction, positive coping style, lack of knowledge about diet therapy, difficulty in obtaining medical food, and weak social support system. Conclusion: The caregivers of children with MMA play an important role in the process of die therapy, and a positive coping styles of caregivers can improve compliance, but there are still many obstacles and problems in the treatment process. Medical staff can unite with caregivers to appeal to all sectors of society to increase attention to children with MMA, and improve children's compliance and prognosis.

Key words: rare disease; Methylmalonic Acidemia; diet therapy; qualitative research