Objective?To study the effect of nasal continuous positive airway pressure (NCPAP) on blood gas indexes in children with severe pneumonia. Methods?A total of 182 children with severe pneumonia admitted to the Jinniu Maternity and Child Health Hospital of Chengdu from February 2018 to July 2019 were selected as the research objects. According to the random number table, they were divided into the control group and the observation group, with 91 cases in each. Children in the control group were treated with conventional comprehensive treatment, and children in the observation group were treated with NCPAP on the basis of the control group. The clinical curative effect of the two groups of children 24 h after treatment, the disappearance time of dyspnea, the time to return to normal heart rate, the length of stay, partial pressure of carbon dioxide (PaCO2), oxygen partial pressure (PaO2), oxygen saturation (SaO2) levels and tracheal intubation rate were compared between the two groups. Results?24 h after treatment, the total clinical effective rate of observation group (97.8%) was higher than that of control group (89.0%); The disappearance time of dyspnea, the time to return to normal heart rate and the length of hospital stay in the observation group were shorter than those in the control group; 24 h after treatment, PaO2 and SaO2 of the two groups of children were higher than before treatment, and the observation group was higher than the control group; PaCO2 of the two groups of children were lower than before treatment, and the observation group was lower than the control group; The observation group had a lower tracheal intubation rate compared with the control group (all P?