Abstract: OBJECTIVE To explore the efficacy of vitamin D₃ assisted therapy on children patients with cough variant asthma(CVA). METHODS The 122 cases of CVA children patients were randomly divided into control group(n=61) and observation group(n=61). Control group was given fluticasone propionate inhalation aerosol + salbutamol sulfate inhalation aerosol, and observation group was given vitamin D₃ on the basis of control group. The clinical symptoms, lung function, T lymphocyte subsets contents and serum 25-dihydroxy vitamin D₃25(OH)D₃, matrix metalloproteinase 9(MMP-9), interleukin-10 (IL-10) before treatment and after 6 months of treatment were compared between the two groups. RESULTS Compared with before treatment, the clinical symptoms scores in the two groups were significantly decreased(P<0.05), and the lung function indexes of forced expiratory volume in one second, forced vital capacity and peak expiratory flow rate in the two groups were increased(P<0.05), and the changes in observation group were significantly greater than those in control group(P<0.05). After treatment, the CD4⁺ and CD4⁺/CD8⁺ in observation group were significantly lower than those before treatment and those in control group(P<0.05) while the CD8⁺ was significantly higher than that before treatment and that in control group(P<0.05). After treatment, the levels of serum 25(OH)D₃ and IL-10 in the two groups were increased(P<0.05) while the level of MMP-9 was significantly decreased(P<0.05), and the changes in observation group were greater than those in control group(P<0.05). There were no obvious adverse reactions in the two groups. CONCLUSION Vitamin D₃ combined with routine therapy can significantly improve the cough symptoms in children patients with CVA, improve lung function, correct the imbalance of T lymphocyte subsets, and promote airway hyperresponsiveness and airway inflammatory response, and it has good safety.