Abstract: Objective: To study the parameter features of lung function in children with chronic cough and its clinical value.Methods: Sixty-eight children(under 6 years of age) with chronic cough including 33 cases of non-asthma and 35 cases of variant asthma(CVA)were detected of the tidal breathing pulmonary function,and the result was compared with that of other 38 cases of typical asthma.Results: There was no difference between non-asthma group and CVA group in the following parameters:tidal volume(VT),rate of respiratory(RR) and time of expiration(TE)(P>0.05);meanwhile,the time of inspiration(TI),time of inspiration/time of expiration(TI/TE),time to peak expiratory flow/time of expiration(TPF/TE),and volume of peak expiratory flow/volume of expiration(VPF/VE) demonstrated significant difference(P<0.05) between the two groups.TPF/TE and VPF/VE in the non-asthma group was obviously higher than that in the CVA group and the other parameters had no statistical significance(P>0.05).Ratio of TI/TE in CVA group was higher than that in typical asthma group(P<0.05),but the difference was not significant between them with other parameters(P>0.05).Conclusions: Lung function test has great value in distinguishing patients with chronic cough with non-asthma and those with cough variant asthma,which may provide clinical basis for the treatment of the disesase.