Objective: To analyze the clinical characteristics and etiology of hypereosinophilia in children. Methods: Clinical data of 88 children with hypereosinophilia admitted in Children's Hospital of Zhejiang University School of Medicine during April 2009 and May 2015 were retrospectively reviewed. The clinical manifestations, etiologies, and the correlation of disease severity with different etiologies were analyzed. Results: The main clinical manifestations were fever, abdominal pain, cough and/or tachypnea, skin rash, hemafecia and diarrhea, which were observed in 19 (21.6%), 15 (17.0%), 14 (15.9%), 13 (14.8%), 11 (12.5%) and 6 (6.8%) cases, respectively. For etiologies, there were 28 cases (31.8%) induced by infections, including 11 cases of acute bronchial pneumonia, 9 cases of parasite infection, 4 cases of septicemia, 2 cases of urinary system infection, 1 case of cellulitis and 1 case of cholecystitis complicated with pancreatitis. The etiologies for the rest cases were allergic diseases (25 cases, 28.4%), eosinophilic gastroenteritis (20 cases, 22.7%), immunodeficiency (3 cases, 3.4%, all were moderate to severe eosinophilia), ABO hemolysis (2 cases, 2.3%), hematologic neoplasms (2 cases, 2.3%), eosinophilic cystitis (1 case, 1.1%), eosinophilic granulomatosis with polyangitis (1 case, 1.1%), nephrotic syndrome (1 case, 1.1%), and 5 cases (5.7%) were of unknown causes. Conclusions: Fever, abdominal pain, cough and/or tachypnea are the most common clinical manifestations in children with hypereosinophilia. Infection, allergic diseases and eosinophilic gastroenteritis are the most common etiologies, and parasites are the most common pathogen identified. Differential diagnosis of primary immunodeficiency should be considered in children with moderate to severe eosinophilia.