To observe the effect of Kechuan Zhending Decoction（咳喘镇定汤）in the treatment of children with cough variant asthma and the effect on eosinophil count（EOS）and interleukin-23（IL-23）/Helper T cells17（Th17）axis.

A total of 104 cases of paediatric cough variant asthma admitted from August 2020 to February 2023 were selected and divided into two groups by simple random method.The conventional group was given the conventional treatment of relieving cough，resolving phlegm，anti-inflammatory，relieving asthma，etc.，and the Kechuan Zhending Decoction group was given the auxiliary treatment of Kechuan Zhending Decoction on the basis of the conventional group.T-lymphocyte subpopulations，EOS，macrophage inflammatory protein-1α（MIP-1α），Clara cell secreted protein 16（CC-16），eosinophil-activated chemokine（Eotaxin），IL-23/Th17 axis and small airway function were detected between and within the groups.Differences in cough symptom scores and TCM symptom scores were assessed between and within groups.The efficacy and adverse reactions were analyzed between groups.

There was no difference in T-lymphoid subgroups，CC-16 or Eotaxin before treatment（P>0.05）.The levels of CD⁺₈，EOS，MIP-1αand Eotaxin decreased and the levels of CC-16，CD⁺₄ and CD⁺₄/CD⁺₈ increased after treatment in both groups，and the levels of CD⁺₈，EOS，MIP-1αand Eotaxin in the Kechuan Zhending Decoction group were lower than those in the conventional group，and the levels of CC-16，CD⁺₄ and CD⁺₄/CD⁺₈ in the Kechuan Zhending Decoction group were higher than those in the conventional group after treatment（P<0.05）.There was no difference in IL-23/Th17 axis comparing that before treatment（P>0.05）.The levels of IL-23，Th17 and interleukin-17（IL-17）decreased after treatment in both groups，and the IL-23/Th17 axis was lower in the Kechuan Zhending Decoction group than that in the conventional group after treatment（P<0.05）.There was no difference in the relevant scores before treatment（P>0.05）.Cough symptom scores and TCM symptom scores decreased after treatment in both groups，and cough symptom scores and TCM symptom scores were lower in the Kechuan Zhending Decoction group than those in the conventional group after treatment（P<0.05）.There was no difference in small airway function before treatment（P>0.05）.Small airway function was elevated after treatment in both groups，and the small airway function was higher in the Kechuan Zhending Decoction group than that in the conventional group（P<0.05）.In the Kechuan Zhending Decoction group，there were 13 cases cured，with a total of 35 cases showing significant effective results.The total effective rate was 92.31%，significantly higher than that in the conventional group（P<0.05）.

Kechuan Zhending Decoction can improve T-lymphoid subsets and small airway function by regulating IL-23/Th17 axis in children with cough variant asthma，reduce the cough symptoms and improve the curative effect.