Objective: To explore the symptom relief and changes in immune inflammatory response in children with severe mycoplasma pneumonia after treatment with high-dose methylprednisolone. Methods: A retrospective analysis was performed on the clinical data of 120 children with mycoplasma pneumonia treated in the hospital from February 2022 to February 2025. All patients were treated with methylprednisolone combined with terbutaline. According to different doses of methylprednisolone, they were divided into conventional dose group (60 cases, 2mg·kg-1·d-1) and high dose group (60 cases, 4 mg·kg-1·d-1). The efficacy, symptom relief time, inflammatory factors, immune function, and adverse reactions were compared between the two groups. Results: The total effective rate in the high-dose group was higher, and the time for fever reduction, pulmonary rales and wheezing was shorter than that in the conventional dose group (P<0.05). After treatment, C-reactive protein (CRP) and interleukin-6 (IL-6) decreased in both groups, but were lower in the high-dose group (P<0.05). After treatment, CD4+ and CD4+/CD8+ increased in both groups, which were higher in the high-dose group. CD8+ decreased in both groups. The high-dose group was lower than that in the conventional dose group (P<0.05). The incidence of adverse reactions did not differ significantly between the two groups (P>0.05). Conclusion: After treatment with high-dose methylprednisolone, the effect of children with severe mycoplasma pneumonia is better. The inflammatory response of the children is significantly reduced, the immune function is significantly improved, the symptom relief time is shortened, and no adverse reactions are increased.