Objective To investigate the clinical features, therapeutic strategies, and outcomes in pediatric patients with severe Mycoplasma pneumoniae pneumonia (SMPP) complicated by intracardiac thrombosis. Methods A retrospective analysis was performed on the clinical records of 19 children diagnosed with SMPP and concurrent intracardiac thrombosis admitted between January 2020 and May 2024. Results Among the 19 children, 13 were boys and 6 were girls, with a median age of 8 (7-10) years. All children presented with fever and cough, and 11 (57.89%) exhibited additional extracardiac thrombotic events. Laboratory findings revealed elevated levels of C-reactive protein 58.91 (25.62-98.19) mg/L, lactate dehydrogenase 559 (442-791) U/L, and D - dimer 6.06 (3.44-7.52) mg/L. The median time from symptom onset to diagnosis was 12 (10-17) days, with all thrombi identified via echocardiography; the majority (n=14, 73.69%) were located in the right ventricle. Six patients underwent immediate surgical intervention due to hemodynamic instability (shock), large thrombus size (diameter>30 mm), or presence of multiple mobile thrombi with high embolic risk. Thirteen patients initially received anticoagulation therapy; seven showed marked reduction in thrombus burden, while one experienced embolization during early treatment and five required conversion to surgical thrombectomy due to inadequate response. During follow-up (3-5 months), none of the 11 surgically treated patients developed new thromboses or cardiac complications. Among the 8 non-surgical cases, 6 achieved complete thrombus resolution within 3 months, while one patient was lost to follow-up and one experienced embolization.Conclusion Pediatric SMPP with intracardiac thrombosis presents with nonspecific symptoms and carries a significant risk of systemic embolization. Dynamic monitoring of echocardiography and D-dimer levels during the first 1-2 weeks of illness is recommended for early detection. Prompt anticoagulant or surgical management is associated with favorable outcomes; however, therapeutic decisions should be individualized based on thrombus morphology, hemodynamic status, and embolic risk.