OBJECTIVE： To investigate the effect of different doses ambroxol hydrochloride on lung protection of patients in perioperative thoracotomy. METHODS： 60 patients in perioperative thoracotomy were randomly divided into control group（30 cases） and observation group（30 cases）. Control group received 30 mg Ambroxol hydrochloride injection from 1 week before surgery to 1 week after surgery， adding into 100 ml 0.9％ Sodium chloride injection， intravenously， twice a day. Observation group received 300 mg Ambroxol hydrochloride injection from preoperative 1 week to postoperative 1 week， adding into 100 ml 0.9％ Sodium chloride injection， intravenously， twice a day. All patients received the second-generation cephalosporin antimicrobial drugs for anti-infection after surgery. lung surfactant-associated protein A （SP-A）， intercellular adhesion molecule （ICAM-1） levels preoperative 1 week and postoperative 1 week， and incidence of postoperative complications in 2 groups were observed. RESULTS： Preoperative 1 week， there were no significant differences in the SP-A and ICAM-1 in 2 groups （P＞0.05）. Postoperative 1 week， SP-A and ICAM-1 in control group and ICAM-1 in observation group were significantly higher than preoperative 1 week， but SP-A and ICAM-1 in observation group were lower than control group， the differences were statistically significant （P＜0.05）， there were no significant differences in SP-A in preoperative 1 week and postoperative 1 week （P＞0.05）. The incidence of postoperative complications in observation group was significantly lower than control group， the difference was statistically significant （P＜0.05）. CONCLUSIONS： The effect of high-doses ambroxol hydrochloride on lung protection of patients in perioperative thoracotomy is significantly superior to small dose， which can reduce the incidence of lung complications.