Objective：To compare the efficacy of 3% hypertonic saline and ambroxol hydrochloride in the treatment of moderate to se－vere bronchiolitis in children. Methods：The 121 children with bronchiolitis were graded when they were on admission according their state of an illness. They were divided into 2 groups randomly. Patients in one group were given aerosol inhalation with 3% hypertonic saline，while those in the other group were given aerosol inhalation with ambroxol hydrochloride，as well as the conventional treat－ment. Three days later，the two groups were all graded again according their state of an illness. Then the difference in efficacy and hospital stay were compared between the two groups. Results：There was no difference in the grades between the two groups when they were on admission（P >0.05）. Three days later，the grades of the two groups were significantly decreased than those before the treatment（P<0.05）. And there was no difference in grades between the moderate bronchiolitis of children（P=0.533）；the grades of severe bronchiolitis of children in the 3% hypertonic saline group were significantly decreased compared with those in the am－broxol hydrochloride group（P=0.013）. There was no difference in hospital stay between the two groups（P >0.05）. Conclusion：The therapies of 3% hypertonic saline and ambroxol hydrochloride are all effective for the moderate and severe bronchiolitis of children，but 3% hypertonic saline is more effective for severe bronchiolitis than ambroxol hydrochloride. There is no significant difference in the hospital stay between the 3% hypertonic saline group and ambroxol hydrochloride group for moderate and severe bronchiolitis of children.