Abstract: Objective:To investigate the clinical characteristics, diagnosis, treatment and prognosis of mycoplasma pneumoniae-associated hemophagocytic syndrome (MP-HPS). Methods:The clinical data of MP-HPS children admitted to Shenzhen Children's Hospital between June 1, 2013 and December 31, 2018 were retrospectively analyzed. Results：The median age of 11 patients with MP-HPS was 3 years and 3 months.There were 5 cases aged younger than 3 years, 6 males and 5 females. Clinical manifestations included fever in 11 cases, cough in 8 cases, diarrhea in 3 cases, and poor mental health in 1 case. All patients had large liver, and large spleen was found in 6 cases. Laboratory examination results showed all of 11 patients had different degrees of hemocytopenia, elevated serum ferritin (≥ 500 μg·L-1) and lactate dehydrogenase.Bone marrow images suggested hemophagocytosis in 11 cases. There were 8 cases of abnormal liver function, 9 cases of high triglyceride, 6 cases of low fibrinogenemia, and 8 cases of decreased NK cell activity. MP infection was confirmed by MP-IgM MP-DNA tests in all 11 cases with 2 cases of combined bacterial infections and 2 cases of fungal infections. No other viral infections were detected. Imaging examination (chest X-ray and chest CT) results showed all of 11 cases presented pneumonia, 7 cases were complicated with pleural effusion, and 1 case was complicated with mediastinal emphysema and subcutaneous emphysema of the neck and chest. Seven cases underwent bronchoscopy and 2 cases had plastic bronchitis. Macrolides were combined with other antibiotics. Glucocorticoid and gamma globulin were used in 10 patients, immunosuppressant (cyclosporin) was used in 4 patients, and cyclosporin + etoposide was used in 1 patient. Among the 7 patients admitted to PICU, 5 were intubated. Nine cases were discharged after improvement and 2 cases died. Conclusion:MP-HPS should be diagnosed early and treated actively. Cytokine storm should be blocked in time to improve the prognosis of children.