Abstract: Objective　To analyze the risk factors of mucous plug caused by Mycoplasma pneumoniae pneumonia (MPP) in children and guide clinical therapy to decrease the incidence of sequela caused by airway inflammatory obstruction. Methods　We conducted a retrospective study of the clinical data of 116 children with MPP who received fiber bronchoscope from January 2012 to January 2014 admitted to the respiratory department of the Children’s Hospital of Hebei provience. Based on the airway mucosal lesions seen through the bronchoscope, the subjects were divided into the mucous plug group (n=67) and the control group (n=49). Gender, age of onset, febrile course, pleural effusion, white blood cell counts, neutrophil ratio, C reactive protein (CRP), serum lactate dehydrogenase level (LDH), initial time of received macrolides and fiber bronchoscope were compared between the two groups. If the results of single factor analysis showed P<0.05, the indicators were analyzed by the logistic regression analysis. The receiver operator characteristic (ROC) curve was drawn to evaluate the predictability of logistic regression model. Results　The results of single factor analysis showed that age of onset, febrile course, CRP, serum LDH, pleural effusion cases in the mucous plug group were higher than those in control group (P<0.05). The results of the logistic regression analysis showed that older than three years (OR=7.45), febrile course more than 10 days (OR=4.01), the level of CRP and LDH higher than 40 mg/L (OR=5.41) and 350 U/L (OR=3.63) were respectively the risk factors of mucous plug caused by MPP in children. The area under the ROC curve is 0.846 (95%CI: 0.773-0.919, P=0.000). Conclusions　MPP children with age older than three years, or with febrile course more than 10 days, or with the level of CRP and LDH higher than 40 mg/L and 350 U/L has the possibility of forming a mucous plug.