Objective:To explore the value of preoperative spiral CT examination in the diagnosis of invaded thoracic aorta by esophageal carcinoma. Methods: All the 100 patients with diagnosed esophageal carcinoma by pathological examination took spiral CT and were analyzed preoperatively. Exist of fat space between e-sophagus and thoracic aorta, the thickness of esophagus wall and the angle of esophagus touched thoracic aorta were the criteria of diagnosis. All the results of spiral CT examination were compared with the results of their postoperative histopathological status. Results:(1) Among 18 cases with fat space between e-sophagus and thoracic aorta disappeared, 14 cases thoracic aorta invaded(77. 78%), 4 cases thoracic aorta noninvaded(12. 22%) ;(2) Among 12 cases with the thickness of esophagus wall less than 1cm, 3 cases thoracic aorta invaded(25. 00%), 9 cases thoracic aorta noninvaded(75. 00%). Among 23 cases with the thickness more than 2cm, 19 cases thoracic aorta invaded(82. 61%), 4 cases thoracic aorta noninvaded(17. 39%). Among 65 cases with the thickness between 1cm and 2cm, 8 cases thoracic aorta invaded(12. 31%), 57 cases thoracic aorta noninvaded(87. 69%). sensitivity, specificity, accuracy were 82. 35%(14/ 17), 95. 18%(79/83), 93. 00%(93/100) respectively; (3) Among 43 cases with the angle of esophagus touched thoracic aorta less than 45 degree, 4 cases thoracic aorta invaded(9. 30%), 39 cases thoracic aorta noninvaded(90. 70%). Among 17 cases with the angle more than 90 degree, 12 cases thoracic aorta inva-ded(70. 59%), 5 cases thoracic aorta noninvaded(29. 41%). Among 40 cases with the angle between 45 and 90 degree, 17 cases thoracic aorta invaded(42. 50%), 23 cases thoracic aorta noninvaded(57. 50%). Accuracy was 85. 00%. Conclusion; Preoperative spiral CT examination has a greater value in the diagnosis of the invaded thoracic aota by esophageal carcinoma.