Abstract: Objective To investigate epidemiological characteristics of pathogenic bacteria of community-acquired lower respiratory tract infection in children in Kunming (with an altitude of 1860 m) .Me thods The results of bacterial culture of 9793 patients with community-acquired lower respiratory tract infection in the Second Affiliated Hospital of Kunming Medical University and Kunming Maternal and Child Health Hospital from Jan 2011 to Nov 2015 were reviewed.Re s ults Among the 9793 phlegm samples from the children patients with community-acquired lower respiratory tract infection, 8433 (86.10%) phlegm samples were qualified, 2918 (34.6%) had a positive bacterial culture.The pathogenic bacteria mainly were gram-negative bacteria (1 839 strains, 58.9%) , and gram-positive bacteria (1 284 strains, 41.4%) . The detection rate of gram-negative bacteria was increasing, among which Haemophilus was in a leading position (768 strains, 24.60%) , followed by Streptococcus pneumonia (665 strains, 21.3%) , E. coli (315 strains, 10.10%) , Staphylococcus aureus (310 strains, 9.9%) , Moraxella catarrhalis (272 strains, 8.7%) , and Klebsiella pneumoniae bacillus (224 strains, 7.2%) . The detection rates of six common bacteria in different seasons were significantly different (P<0.05) . The detection rates of six common bacteria except Moraxella catarrhalis in different age groups were significantly different (P<0.05) . Conclus ions Gram-negative bacterium was the main pathogenic bacteria for those children who got community-acquired lower respiratory tract infections. Haemophilus influenza was the most common pathogenic bacteria and the detection rate of pathogenic bacteria in winter was high. The most common pathogenic bacteria in infants and toddler were Haemophilus influenza. The most common pathogen in preschool and school-age children was Streptococcus pneumonia.The pathogenic bacteria of lower respiratory tract infection in the children community of Kunming are different from those in the plain area.