Objective To study the clinical characteristics and CT diagnosis results of children patients with severe adenovirus pneumonia. Methods A total of 154 children patients with adenoviral pneumonia admitted to our hospital from December 2016 to December 2017 were included in the study. The clinical manifestations and CT diagnostic features were analyzed. Results The ratio of male to female in children patients with adenovirus pneumonia was 1.96:1, and the age was concentrated in 6 months to 2 years (79.22%), and the onset season was concentrated in spring and winter (71.43%), and the treatment effect was generally good. The main clinical symptoms were fever, cough and asthma, and 89.64% and 61.04% children patients had lung wet rales and lung wheezing rales. Laboratory tests showed that 86.36% children patients had elevated muscle zymogram, and 50.65% with increased CRP and 40.26% with elevated WBC. Children patients were divided into general group (general adenovirus pneumonia, n=104) and severe group (severe adenovirus pneumonia, n=50). X-ray films of severe group and general group were with lung texture changes, emphysema and lobular parenchymal infiltration, but the emphysema, unilateral consolidation, lung segment and large leaf parenchymal infiltration in children patients with severe adenovirus pneumonia were more severe than those in children patients with general adenovirus pneumonia. Chest CT examinations of severe group and general group showed lung parenchyma changes, double lungs involvement, consolidation and centripetal distribution and small airway changes. However, the double lungs involvement, involved lung lobes ≥3, and consolidation and centripetal distribution, cluster-like shadow, air bronchogram, small airway change and pleural thickening in children patients with severe adenovirus pneumonia were more severe than those in general group. Conclusion X-ray films of severe adenovirus infection have pulmonary interstitial changes, consolidation, lobular parenchymal infiltration and infiltration of lung and lobes. CT is characterized by multiple cluster-like parenchyma of double lungs, and the parenchyma have high density, fuzzy edges and uniform enhancement, and they are mostly distributed in a centripetal manner, and small airway changes are more serious.