Abstract: Objective To analyze the clinical feature and common etiology of diffuse alveolar hemorrhage (DAH) in children. Methods Clinical data from 138 children with initially diagnosed DAH were retrospectively analyzed. The etiology, diagnosis, treatment, and prognosis had been summarized. Results Among 138 children, 76 were male and 62 were female. The clinical features are pallor (130 cases, 94.2%), cough (86 cases, 62.3%), fever (74 cases, 53.6%), anhelation (67 cases, 48.6%), hemoptysis (59 cases, 42.8%) and dyspnea (43 cases, 31.2%). Chest imaging changes were mainly patch shadow and ground glass shadow. Moreover, the detection rate of hemosiderin cells in sputum, gastric juice and bronchoalveolar lavage fluid was 90.8% (79/87). The common underlying diseases that caused DAH were idiopathic pulmonary hemosiderosis (65 cases), hematological system disease (22 cases), vascular inflammatory diseases (15 cases), infectious diseases (14 cases) and cardiovascular disease (5 cases). The mortality rate in acute phase of DHA was 23.2% (32/138). Conclusions DHA is a life-threatening clinical emergency disease, its cause was complex and diverse, and the acute mortality rate is high. Glucocorticoid is the first choice of treatment for majority of patients.