Objective To study the clinical efficacy and effects on CRP levels of ambroxol in treatment of pulmonary infections.Methods 68 patients with pulmonary infection were selected and divided into the observation group(n =34)and control group by using the random number table method(n =34).The observation group was treated with ammonia bromine atomization inhalation treatment,while the control group was treated with alpha chymo-trypsin atomization inhalation therapy.The clinical effect and duration of symptoms and signs disappeared of the two groups were compared,and serum CRP level changes in the two groups before and after treatment were also compared. Results After treatment,the clinical total effective rate was 91.2% of the observation group.And the total effective rate was 70.6% in control group,the comparison between the two groups had statistically significant difference (χ2 =4.316,P <0.05).Compared with the control group,the observation group patients symptoms disappear time(3.1 ± 0.5)d,pulmonary symptoms disappear time(4.1 ±1.7)d,body temperature returned to normal time(4.1 ±1.6)d and hospital stay(8.4 ±2.8)d were significantly shortened,the differences were statistically significant (t =2.879, 2.918,3.025,3.972,all P <0.05 ).The serum CRP levels in patients of the observation group was (22.45 ± 9.27)mg/L,which of the control group was (33.45 ±14.67 )mg/L,both were significantly lower than before treatment,the difference was statistically significant (t =6.314,5.126,all P <0.05).The lower degree of serum CRP level in the observation group was obviously better than tha in the control group,the difference was statistically significant (t =6.263,P <0.05).Conclusion The ambroxol can achieve significant clinical effect on treatment of pulmonary infections,which can significantly shorten the patientˊs symptoms and lung signs disappear time and length of hospital stay,etc.It can reduce the serum CRP level,and is worth popularization and application in clinic.