PurposeThe study was conducted to analyze the role of respiratory microbiome composition in children pneumonia etiology diagnosis. MethodsThe bronchoalveolar lavage fluid bacterial community between the Mycoplasma pneumoniae pneumonia (MP group, n = 13) and the pathogen negative pneumonia (N group, n = 20) children were compared using the full-length 16S rRNA gene sequencing. ResultsDistinct bacterial communities were identified in two groups and lower α-diversity was revealed in the MP patients indicating the lower abundance microbiota composition. Dominant bacteria were Mycoplasma and Mycoplasma pneumoniae for MP patients at genus and species levels. Possible pathogens were characterized in 17 out of 20 patients in the N group by detection of higher abundance using the 16S rRNA gene sequencing. ConclusionsThe high taxonomic resolution of full-length 16S rRNA gene sequencing assists in improving characterization of potential pathogens, and more studies are necessary to further evaluate the prognostic roles of specific bacteria in the pathogenicity of pneumonia.