Abstract： Objective To observe the effect and adverse reaction of ambrocol oral solution on treatment of children with lower respiratory tract infection. Methods 160 children hospitalized with lower respiratory tract infection in children according to odd and even numbers were randomly divided into two groups on the basis of conventional therapy,the treatment group were given oral ambrocol oral solution,the control group treated with oral ambroxol hydrochloride syrup.The clinical efficacy and adverse reaction were observed. Results 62 cases were excellent,effective in12 cases,not effective in 6 cases,total effective rate 92.5 %,and the control group 50 cases,15 cases,81.3 % compared to the total effective rate between the two groups was statistically significant(x2=4.44,P＜0.05＝; treatment group cough disappearance time(4.5 ± 1.4)d,expectoration difficulties disappear time(3.1 ± 1.2)d,wheeze disappearance time(2.9 ± 1.2)d,and the control group(5.4 ± 1.5)d,(3.5 ± 1.2)d,(3.7 ± 1.4)d phase by comparison,the differences were statistically significant(t=3.930,2.105,7.767,all P <0.05). Conclusion Ambrocol oral solution is appropriate for children of all ages expectorant cough medicine,high efficacy ,safety ,and can improve the clinical effects of lower respiratory tract infection.