Objective To study the etiology and clinical features of pleural effusion in Children .Methods The clinical data of 117 cases who diagnosed with pleural effusion in children were analyzed retrospectively .Results In the study ,infectious pleural ef-fusion that were 97 cases(82 .9% ) ,in which 79 cases caused by suppuration(67 .5% ) ,9 cases caused by mycoplasma(7 .7% ) ,6 ca-ses caused by virus (5 .1% ) ,3 cases caused by tuberculous-empyema (2 .6% ) .Non-infection cause included 20 cases (17 .1% ) ,in which 6 cases of nephrotic syndrome ,4 cases of malignant tumor(1 case of lung cancer ,1 case of lymphoma ,1 case of leukemia ,1 case of nephroblastoma and lung metastasis) ,4 cases of Kawasaki disease ,2 cases of acute glomerulonephritis ,2 cases of industrial vinegar concentrate poisoning ,2 cases of hemolytic uremic syndrome ,1 case of hypereosinophilic syndrome .There were 83 cases cured in 117 cases of pleural effusion ,26 cases left hospital with getting better ,7 cases of no cure(4 cases of malignant tumor ,1 case of nephrotic syndrome ,2 cases left hospital automaticly )and 1 case of death .Conclusion Infection is the main cause of pleural effu-sion in children ,it should be pay attention to pleural effusion in children caused by various diseases in the process of clinical diagno-sis and treatment .