Objective:To explore the effect and mechanism of Qingfei Mixture（清肺合剂）, a Chinese medicine,in treating mycoplasma pneumonia (MP) in MP patients and rat model.Methods:A total of 46 MP children with phlegm heat obstructing Fei (Lung) syndrome were randomly assigned to two groups by the method of random number table,with 23 children in each group.The control group was treated with intravenous infusion of azithromycin;the treatment group received intravenous infusion of azithromycin and oral administration of Qingfei Mixture.The treatment course was 7 days.Major symptoms and minor symptoms were observed and scored before and after treatments.A rat model of MP was also established.A total of 120 wistar rats were randomly divided into 5 groups:a normal group,infection group,Qingfei Mixture treatment group,azithromycin treatment group,and Qingfei Mixture + azithromycin treatment group.Each group contained 24 rats,from which every 6 were euthanatized 1,3,7 and 14 days after infection.MP DNA in pulmonary tissue homogenates was detected using real-time fluorescence quantitative polymerase chain reaction.Pathology was assessed after hematoxylin (HE) staining and lung tissue pathology scores were determined in pulmonary tissue.Transmission electron microscopic detection and electronic image analysis were performed on lung tissue 3 days after infection.Interleulin (IL)-17 was detected in serum using enzymelinked immunosorbent assay (ELISA) 7 days after infection.Remlts:In the clinical study,both control and the treatment group showed improved results on removing symptoms of phlegm heat syndrome compared to the control group (P＜0.05).In animal experiments,On the 7th day after MP infection,as detected by electron microscopy,the pulmonary capillary basement membranes of the azithromycin + Qingfei Mixture treatment group were much thinner than those of the azithromycin or Qingfei mixture treatment groups (P＜0.05).The level of serum IL-17 in the azithromycin + Qingfei Mixture treatment group was lower than that in the azithromycin or Qingfei Mixture groups (P＜0.01).Conclusion:Both Qingfei Mixture and azithromycin have therapeutic effects on mycoplasma pneumoniae pneumonia,but the combination of both agents had the greatest effect.