To evaluate the efficacy of interferon inhalation by PARI inhaler boy with bronchiolitis, 110 children were randomly divided into two groups. Group 1 included 64 cases who received interferon inhalation by PARI inhaler boy(made in Germany) and the other 46 patients who didn' t received interferon by PARI inhaler boy served as group 2. The effects were compared between the two groups in term of wheezing rale disappearance time, rale absorbing time and hospital stay time. Our results showed that wheezing rale disappearance time in group 1 was shorter than that in group 2( t = 6. 143, P＜ 0.01 ); rale absorbing time in group 1 was significantly shorter than that in group 2 ( t = 2.03, P＜0.05); hospital stay time in group 1 was significantly shorter than that in group 2( t = 3. 195, P＜0.0). It is concluded that interferon inhalation by PARI inhaler boy is an effective auxiliary treatment forbronchiolitis.