Mycoplasma pneumoniae pneumonia (MPP) is mostly benign and self-limiting. After regular treatment with macrolide antibacterial drugs, most of them can heal themselves, but severe MPP will have serious complications, such as hypoxia and respiratory failure. Therefore, this article conducts clinical research on children's MPP and extrapulmonary complications based on the disinfection of smart big data(BD) medical equipment, discusses the clinical characteristics and changes of lung function in children with MPP in different degrees of illness, and provides a certain theoretical basis for the timely diagnosis and treatment of children with MPP. This article adopts a retrospective analysis method to select 88 MPP patients who were hospitalized in a pediatric department of a hospital from March 2019 to February 2020. According to the severity of the disease, they were divided into a severe MPP group and a mild MPP group. According to their clinical manifestations, they were divided into a severe MPP group and a mild MPP group. The wheezing group and the non-wheezing group are divided into the acute phase and the recovery phase according to the period of the disease. The clinical manifestations, laboratory indicators, chest imaging findings, and complications are compared and analyzed. The experiment proved that there were 33 cases in the severe MPP group, the average duration of fever was 11.09±4.72 days, the average duration of cough was 17.46±3.37 days, and the average hospital stay was 11.32±5.47 days; there were 55 cases in the mild MPP group, and the average fever the duration was 8.59±3.79 days, the average duration of cough was 13.89±3.97 days, and the average hospital stay was 6.97±2.29 days. This shows that the disinfection of medical equipment based on smart BD plays a role in the treatment of children's MPP and extrapulmonary complications, and provides a certain theoretical basis for the clinical treatment of children's MPP.