Objective To investigate the clinical characteristics and high-risk factors of bronchial mucus plugs formation in children with lobar pneumonia.Methods Children with lobar pneumonia treated from January 2018 to March 2020 were selected as the study subjects. According to the results of fiberoptic bronchoscopy, the children were divided into the mucous plugs group and the non-mucous plugs group, and the clinical characteristics and laboratory examination results of the two groups were compared.Results A total of 935 children with lobar pneumonia were treated. According to fiberoptic bronchoscopy, 135 patients (73 boys and 62 girls) were included in the mucous plugs group, and the median age was 5.0 (3.1-7.0) years. There were 135 children (75 boys and 60 girls) in the non-mucous plugs group, and the median age was 5.8 (4.0-7.0) years. Compared with the non-mucous plugs group, the mucous plugs group had a longer fever duration, a higher percentage of neutrophil, higher levels of c-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), D-2 dimer and CD4/CD8, and a lower platelet count, with statistical significance (P<0.05). Mycoplasma pneumoniae was the main pathogen in both groups. The proportions of Mycoplasma pneumoniae infection, Mycoplasma pneumoniae combined with bacterial infection, Mycoplasma pneumoniae combined with virus infection and Mycoplasma pneumoniae combined with Epstein-Barr virus infection in the mucous plugs group were 92.6%, 20.7%, 51.1% and 14.1%, respectively, which were higher than 77.0%, 11.9%, 20.0% and 0.7% in the non-mucous plugs group, and the differences were statistically significant (χ²=3.91-28.51, P<0.05). The proportion of infection sites in the lower lobe of lung and left lower lobe of lung in the mucus plugs group was higher than that in the non-mucus plugs group, and the incidence of pleural effusion, liver function injury and sequelae was higher than that in the non-mucus plugs group, and the differences were statistically significant (P<0.05). The results of binary logistic regression analysis suggested that LDH and CD4/CD8 were independent risk factors for the formation of mucous plugs in lobar pneumonia (P<0.05).Conclusions The formation of bronchial mucus plugs in children with lobar pneumonia is related to LDH and CD4/CD8.