Abstract: Objective To explore the level of fractional exhaled nitric oxide(FeNO) in asthmatic children aged 6 year old and above,and its correlation with age,peripheral blood eosinophilia count(EOS%),FEV1% and FEV1/FVC. Methods A total of 70 asthmatic children(age≥6 years) were enrolled and divided into acute exacerbation group and remission group with 21 healthy children as controls.Lung function,FeNO and EOS were measured for all children. Results ①There was no statistical differences in FeNO and EOS between acute exacerbation group and remission group(P＞0.05),and there was significant statistical differences between asthmatic children and healthy children(P＜0.05).FEV1% and FEV1/FVC among acute exacerbation group,remission group and control group were different(P＜0.05),and FEV1% and FEV1/FVC in the remission group were different from the control group(P＞0.05).②FeNO had positive relationship with age(r=0.259,P＜0.05) and EOS% (r=0.151,P＜0.05),and had negative relationship with FEV1/FVC (r=-0.151,P＜0.05),and had no correlation with FEV1/FVC(r=-0.12,P＞0.05). Conclusion FeNO can stand for the levels of eosinophilic inflammation.It is helpful for early diagnosis about asthma through FeNO and FEV1/FVC,but age could be taken into account.