Objective To study the therapeutic effect and mechanism of Xiaoer Kechuanning Oral Liquid（oral liquid for pediatric cough and asthma）for respiratory syncytial virus（RSV）infection and bronchiolitis.Methods Totally 68children with RSV infection and bronchiolitis were randomized into the treatment group and control group.Both groups were given routine western medicine.The treatment group was added with Xiaoer Kechuanning Oral Liquid.The treatment lasted for 7 days.The improvement of coughing

wheezing

throat phlegm

pulmonary rales and Bierman’s score was observed.The level of urinary leukotriene E4（LTE4）was detected before and after treatment.Results The total effective rate of the treatment group and control group was 97.05%and 88.24%respectively

with a significant difference between groups（P<0.05）.The treatment group was superior to the control group in relieving coughing

throat phlegm and pulmonary rales and shortening hospital stay（P<0.01）.On the 3rd day after treatment

the wheezing score and Bierman’s score in the treatment group were significantly lower than that in the control group（P<0.05）.The levels of LTE4were significantly decreased in both groups after treatment（P<0.05）

but with no significant difference between groups on the 7th day after treatment（P>0.05）.Conclusion Xiaoer Kechuanning Oral Liquid is effective for RSV infection and bronchiolitis in children and it can relieve coughing

wheezing

throat phlegm and pulmonary rales

shorten hospital stay and increase clinical efficacy.