Objective To investigate the value of echocardiography application in the diagnosis of large amount of pericardial effusion (PE) in children by retrospective etiology and prognostic analysis.Methods A total of 68 children with large amount of PE admitted in Beijing Children's Hospital,Capital Medical University from March 2010 to March 2016 were reviewed retrospectively,and the echocardiographic presentations,etiology diagnosis,treatment,and prognosis were analyzed.Results Analysis indicated that the etiology diagnosis ratio was 97.1％ (66/68 cases),the effective ratio of the medical treatment was 71.8％ (46/64 cases),and the mortality rate was 7.8％ (5/64 cases).The morbidity was ranked from high to low as follow:large amount of PE included infectious pericarditis 27 cases,tumor associated PE 14 cases,postpericardiotomy syndrome and cardiotrauma 14 cases,systemic diseases 6 cases,vasa lymphatic related diseases 5 cases and idiopathic PE 2 cases.PE resulted from tumor associated PE and vasa lymphatic diseases had lower cure rate than the overall cure rate,and there were statistical significance (28.6％ vs.71.8％,x2 =9.092,P =0.003;20.0％ vs.71.8％,x2 =5.059,P =0.018).Thirty-five children received pericardiocentesis or fenestration drainage.Chylopericardium was restricted to vasa lymphatic diseases.All tumor associated PE had the hemorrhagic PE.The strong echo point in the pericardial cavity might indicate implication for hemorrhagic PE (x2 =5.166,P =0.023).The abnormal mass detected by echocardiography might indicate the tumor related or infectious causes.Conclusions The etiology of large amount of PE could be determined in most of children.As the preferred diagnosis method,echocardiography could help etiological diagnosis combined with clinical manifestation.