Abstract： Objective： To observe the clinical efficacy of modified Qingjin Huatan Decoction combined with Azithromycin sequential therapy in the treatment of severe mycoplasma pneumoniae pneumonia （SMPP） of phlegm-heat obstructing the lung type in children on the basis of the conventional symptomatic treatment. Methods：A total of 88 pediatric patients with SMPP of phlegm-heat obstructing the lung type admitted to the Department of Pediatrics， Pingdingshan Hospital of Traditional Chinese Medicine from October 2022 to October 2024 were selected and divided into the observation group and the control group using the random number table method，with 44 cases in each group. Both groups received conventional symptomatic treatment. The control group was treated with Azithromycin sequential therapy based on such regimen，while the observation group was treated with modified Qingjin Huatan Decoction on the basis of the control group′s regimen. The treatment course for both groups covered 12 days. The clinical efficacy， symptom and sign relief time， as well as the humoral immune indicators [immunoglobulin （Ig） A， IgG， IgM]， and cellular immune indicators （CD3+ ， CD4+ ， CD4+/CD8+） before and after treatment were compared between the two groups. The safty during treatment was recorded. Results：After treatment，the total effective rate in the observation group was 95.45%（ 42/44），which was higher than 79.55%（ 35/44） in the control group（ P＜0.05）. The disappearance times of fever， cough， expectoration， and pulmonary rales in the observation group were shorter than those in the control group （P＜0.05）. The levels of serum IgG and IgM decreased in both groups compared with those before treatment（ P＜0.05），and the levels of serum IgG and IgM in the observation group were lower than those in the control group （P＜0.05）. There were no significant differences in serum IgA levels within or between groups before and after treatment （P＞0.05）. After treatment，the levels of CD3+，CD4+，and CD4+/CD8+ value were increased in both groups compared with those before treatment （P＜0.05）， and the levels of CD3+ ， CD4+ ， and CD4+/CD8+ value in the observation group were higher than those in the control group （P＜0.05）. During treatment，one case of mild diarrhea occurred in the observation group，which resolved spontaneously without intervention；no other drug-induced adverse reactions were observed in the other children. Conclusion： Based on conventional symptomatic treatment， the application of modified Qingjin Huatan Decoction combined with Azithromycin sequential therapy for severe SMPP of phlegm-heat obstructing the lung type can improve clinical efficacy， promote symptom relief， enhance immune function，and has good safety.