Objective:This article explored the value of CT expression and diagnosis of foreign body in the trachea and bronchus.Methods:The results of CT scanning of 50 cases of foreign body in the trachea and bronchus were retrospectively analysed,which were all verification by clinical and drawing out with fibrescope.Results:4 cases of foregign body in the trachea,31 cases of foreign body in the right major bronchus,15 cases of foreign body in the left major bronchus.CT expression:①the self of foreign body;②localized bronchus obstruction,the bronchus under it inflated air or slightly dilated;③mediastinal displacement andtwo margins;④thoraxtwo margins;⑤emphysema;①and ② are the most imporant of them.Conclusion:CT scanning not only makes differential diagnosis but also shows directly the self of foreign body,which is superior to ordinary x ray examination.