Objective To evaluate the clinical application of multi-slice spiral CT(MSCT)for foreign body of trachea or bronchus in children.Methods Twenty cases suspected foreign body were examined with MSCT.The post-processing reconstruction included multiple planar reconstruction(MPR),CT virtual bronchoscopy(CTVB),shaded surface display(SSD),minimum intensity projection(MinIP),and volume rendering(VR).Results The foreign bodies located at trachea in 1 case and at bronchia in 19 cases.The foreign bodies included 18 fragments of peanut and melon seeds,one shrimp and one plastic-tube.All cases were confirmed by fiberoptic bronchoscopy or course of diseases.The position and form of foreign bodies,as well as the relationship between foreign bodies and bronchial muous membrane could be showed by MPR,CTVB,SSD,MinIP and VR.Conclusion MSCT scanning is a significant noninvasive and sensitive diagnostic technique in detecting the foreign body in trachea or bronchus.