Objective To explore the predictive value of lactate dehydrogenase (LDH) for the severity of adenovirus pneumonia in children. Methods A retrospective analysis of the clinical data of 488 hospitalized children diagnosed with adenovirus pneumonia from October 2017 to December 2019 in Shenzhen Children's Hospital. According to the severity of the disease, it is divided into severe group (125 cases) and mild group (363 cases). The Mann-Whitney U test was used to compare the differences in the expression of LDH between the two groups of children, and the ROC curve was used to predict the occurrence of severe adenovirus pneumonia, and to determine the critical value of specific indicators. Results Pairwise comparison between the two groups of data showed that the LDH level of the severe group was significantly higher than that of the mild group, and the difference was statistically significant (P<0.05). Perform ROC curve analysis on the LDH level. When the LDH value is 599U/L, the AUC (area under the curve) is 0.724. The sensitivity to predict severe adenovirus pneumonia is 57.6% and the specificity is 76.9%. Conclusion LDH has a certain predictive value for the severity of childhood adenovirus pneumonia. Early and timely detection of children's plasma LDH levels is of great clinical significance for the evaluation of the severity and prognosis of the disease, as well as early active intervention and treatment.