Abstract: Objective：To explore the etiology and clinical characteristics of pleural effusion in 226 children and to provide evidence for its clinical treatment.Methods：The clinical data of 226 children with pleural effusion who were treated in Hunan Children's Hospital from Jan. 2013 to Jan. 2014 were including symptoms, signs, imaging examinations, and biochemical tests of pleural effusion.Results：(1)Infectious factors ranked the first; there were 209 cases(92.5%,209/226) of infectious pleural effusion, and 172 cases were clinically considered as bacterial pleural effusion, of which the first diagnosis was severe pneumonia in 48 cases(22.9%), and measles with pneumonia in 3 cases(1.4%); there were 72 cases of Mycoplasma pneumniae infection(31.8%); 17 cases were irrelevant to infectious factors(7.5%).(2)Thoracentesis was performed in 50 cases, and 48 cases were in accordance with exudative change, 2 cases with leaking change.(3)There were 75 cases(33.2%) of positive phlegm culture.(4)Mycoplasma pneumoniae infection was obviously fewer in children under 3 than in those at or over 3 years old; tuberculous infection was only in the children over 7; the children at or under 3 years old accounted for higher proportion than before in Mycoplasma pneumonia infection.(5)Average hospital stay was 16d.Conclusion：Infectious factors ranks the first in the causes of pleural effusion; the number of children with pleural effusion resulting from the same cause is different in different age groups, and the children at or under 3 years old account for higher proportion than before in Mycoplasma pneumoniae infection. The hospital stay of children with pleural effusion is comparatively long.

Key words: Pleural effusion, Etiology, Mycoplasma pneumoniae, Infection, Children