Abstract: Objective: To study the effect of MDSCs, IL-23/Th17 axis on CVA through detected the levels of MDSCs, IL-23 and IL-17 in children with cough variant asthma (CVA), Methods: 85 patient children with CVA were randomly selected during 2011 OCT~2013 OCT as the observation group. The observation group was divided into four groups (CVA1~CVA4 grade group) according to the severity of asthma. The percentages of MDSCs on peripheral blood mononuclear cells (PBMCs) were detected by flow cytometry. The levels of IL-23 and IL-17 in serum were detected with enzyme inked immunosorbent assay (ELISA). Results: Compared with the control group, in the CVA groups MDSCs%, IL-23 and IL-17 were gradually increased（P<0.05）. The levels of IL-23 and IL-17 in CVA2~4 grade groups were dramatic increased（P<0.01）, and MDSCs% in CVA3~4 grade groups were also dramatic increased（P<0.01）. The levels of IL-23, IL-17 and MDSCs% in CVA 4 grade group were higher than those in CVA1~2 grade groups（P<0.05）. Also, The levels of IL-23, IL-17 and MDSCs% in CVA 3 grade group were higher than those in CVA1grade group（P<0.05）. Spearman rank correlation showed, MDSCs% and IL-23, IL-17 had the positive correlate in CVA groups(r=0.9655, 0.9452; P=0.0012, 0.001). Conclusion: The levels of IL-23, IL-17 and MDSCs were obviously increased with the severity of CVA gradually aggravated, that shows MDSCs may play an important role in the pathogenesis of CVA. The mechanism may be MDSCs up-regulating the accumulation of IL-23, activating the IL-23/ Th-17 axis, increasing the expression of IL-17 and other inflammatory factors, accelerating the development of CVA chronic inflammation.