Objective To investigate the clinical value of 64 slice spiral CT in the diagnosis of extrahepatic bile duct carcinoma. Methods 44 cases of patients with extrahepatic bile duct carcinoma confirmed by surgery and pathology or biopsy were included in the study. The CT imaging data were retrospectively analyzed. The CT findings of extrahepatic bile duct carcinoma and the diagnostic value of 64 slice spiral CT were summarized. Results Most of extrahepatic bile duct carcinomas were mass type, followed by tube wall infiltration type and intracavity papillary ones were rare. Most hilar cholangiocarcinomas were mass type and the CT density was inhomogeneous, with fuzzy boundaries. Those with tube wall infiltration were with irregular wall thickening and some were with luminal stenosis. CT of intracavity papillary type showed irregular nodular shadow, protruding into the lumen. In terms of middle and distal bile duct carcinoma, intracavity papillary lesions were the most, followed by wall infiltration type and the imaging findings were similar to those of anal bile duct carcinoma. Conclusion 64 slice spiral CT with reconstruction technique is a ideal imaging means of diagnosing extrahepatic bile duct carcinoma.