Purpose investigating the features of ultrasonography in the diagnosis and treatment of children with Mycoplasma pneumoniae pneumonia(MPP), to promote the clinical application of lung ultrasound in department of paediatrics.Materials and methods study collected data from the pediatric department of Erdos Central Hospital from 01 September2016 to 01 March 2017 (43 cases), diagnosed as MPP. Dynamic observation of ultrasound in the treatment of all children. By comparing the characteristics of ultrasound images in different time after treatment, the clinical therapeutic effect was evaluated.All of the patients were treated with macrolides.All children were examined by ultrasonography at the time of admission, 3 days after treatment and discharge.Pleural line, A-line, B-line, pulmonary consolidation and pleural effusion were observed before and after treatment in order to evaluate the therapeutic effect.Results Lung ultrasound was successfully performed in all patients with good imaging quality.The ultrasound features of 43 cases MPP were abnormal pleural line(100%), B- line appeared (100%), B-line appeared that A-line disappeared, subpleural localized pulmonary consolidation (81%), pleural effusion (7%). After treatment of 4 days,the ultrasound features were pleural line abnormalities (42%), B-line (77%),subpleural localized pulmonary consolidation (19%), pleural effusion (7%).Lung ultrasound exam were repeated before discharge.The pleural line and A-line returned to normal.A little lung field scattered with B-line and 2 of 43cases with pulmonary consolidation .After 2 weeks of discharged follow-up , the pulmonary consolidation were disappeared.The positive rate of pleural line abnormalities,B-line, pulmonary consolidation and pleural effusion of different time were test by Pearson Chi-Square test: all P values were less than 0.05.