Objective To study the imaging features of Mycoplasma pneumoniae in multislice spiral CT, and to explore the value of HRCT in the diagnosis and evaluation of mycoplasma pneumonia in children. Methods A retrospective analysis of 72 children admitted to the outpatient department and inpatient department between January 2015 and January 2016 in our hospital (they were diagnosed as Mycoplasma pneumonia by pathology and etiology). The imaging data and clinical data of 72 children were collected and the CT features were analyzed, and the diagnostic value of CT in children with mycoplasma pneumonia and the evaluation of their efficacy were summarized. Results Of the total children, 37 had unilateral lesions and 35 had bilateral lesions. In addition, 19 lesions were located in the left upper lobe, 24 lesions were located in the lower left lobe, 21 lesions were located in the right upper lobe, 13 lesions were located in the right middle lobe and 25 lesions were located in the right lower lobe. The main CT features of the lesion before treatment were as follows: a large area of patchy and speckled shadows appeared, the lungs of the children increased, and the cords or ground-glass shadows appeared. The major CT findings of the lesion after treatment were: reduced density of the lesion, reduced lesion size, and reduced absorption of the patchy lesion after the lesion was treated. Conclusion CT diagnosis of mycoplasma pneumonia in children with lesions clearly showed that its unique image signs combined with clinical symptoms can effectively improve the diagnostic accuracy of patients. In addition, the CT scan can be based on changes in the characteristics of the lesions to evaluate the effect of its cure, the evaluation of the efficacy is of great value and can be used for clinical diagnosis of pediatric mycoplasma pneumonia and efficacy evaluation.