【Abstract】 Objective To explore the significance of exhaled nitric oxide (FeNO), eosinophils (EOS) and immunoglobulin E (total IgE) in the diagnosis of asthmatic diseases in children. Methods From November 2016 to July 2017, 55 children with asthma were selected as asthma group, 55 children with bronchopneumonia as pneumonia group, and 55 children came to our hospital for physical examination in the same period were selected as healthy group. The general data of three groups of children were collected. The differences of FeNO, EOS and total serum IgE between healthy group and asthma group were compared. The levels of FeNO, EOS and total IgE were compared between pneumonia group and wheezing group. The lung function indexes of the three groups were compared. Results The levels of FeNO, EOS and serum IgE in asthmatic group were significantly higher than those in healthy group (P＜0.05). The FeNO, EOS and total IgE in asthma group were significantly higher than those in pneumonia group (P＜0.05). There was no significant difference in VT, RR, vptef/V and tptef/TE among the three groups (P＞0.05). Conclusion FeNO, EOS and IgE have very high specificity and sensitivity in the diagnosis and differentiation of children's asthma. These three indexes are significantly increased in children with asthmatic diseases. Clinical related medical care can give children more timely and effective treatment according to the above three indexes.