Objective:To investigate the effects of preventing asthma of the montelukast combined with budesonide after bronchiolitis.Methods:67 cases of bronchiolitis were divided into two groups randomly,34 cases in treatment group were treated with oral montelukast and budesonide inhalation after bronchiolitis.The control group was not treated.Two groups were observed for two years,and counted all the patients of asthma.Results:Compared with control group,the incidence rate of asthma attack in two years of the treatment group was significantly decreased,and the difference was statistically significant(P0.05).Conclusion:Oral montelukast combined with inhalation budesonide can reduce the incidence rate of asthma after infants bronchiolitis.The method is safe and convenient.