Abstract: 　Objective　To investigate the underlying causes, clinical characteristics, treatment and prognosis of nontraumatic pneumomediastinum (PM) in children. Methods A retrospective analysis of the clinical data of 64 children diagnosed with non-traumatic PM in Yuying Children’s Hospital Affiliated to Medical University from Jan 2003 to Dec 2013 was performed. Nineteen children with SPM and the other 45 with clear causes of non-traumatic PM were divided into two groups for comparison. According to age, 64 cases were divided into 0-6y group and 6-18y group for further comparison. Results A total of 64 patients with non-traumatic PM were collected. Nineteen of them aged 14.90±2.00 y had SPM with unknown etiology, and 84.2% were male. The other group of 45 patients aged 4.26±4.45y, and 55.6% of this group were male. The common causes were pneumonia or other lower respiratory tract infection, asthma and foreign body inspiration. The patients with SPM were always with chest pain. While the patients with clear causes of non-traumatic PM were more complained of dyspnea, coughing, subcutaneous emphysema. The treatment of patients with SPM was bed rest, oxygen uptaking, antitussive, anti-infection and other conservative therapy. All the patients with clear causes of non-traumatic PM had favorable prognosis with the treatment of actively curing primary disease and timely mediastinal air drainage, subcutaneous air drainage and thoracic close drainage. In 35 cases younger than 6 years old, the most common causes were pneumonia or other lower respiratory tract infection, none had SPM. In 29 cases older than 6 years, 19 of them had SPM. Conclusions Etiologies of pneumomediastinum varied with age in children,which should be vigilantly examined, especially for those younger than 6 years old. The key of the treatment to nontraumatic PM with clear etiologies was to treat its primary disease.