Objective To investigate the CT findings of true and false cavities in aortic dissection (AD). Methods 24 cases of AD from 2014 to 2017 in our hospital were collected. The CT findings were retrospectively analyzed, and the true and false lumen manifestations of AD were evaluated and observed. Results The spider web signs 13 cases, all in the false cavity. Twenty-three cases were found in the beak, 18 were in the false cavity, one was in the real cavity, and four were in the true cavity. There were 19 cases of intracavitary thrombosis, 18 of which were in the sham cavity. 83.7 false cavities are larger than the true lumen; The true lumen of the arterial period was higher than that of the false cavity, and the phleural cavity was higher than the true cavity. Diaphragm in the bending direction, a total of 81 lesions, 46 segment to the false lumen, 29 straight section, to the true lumen 4, paragraph 1 in the upper part to the true lumen, the lower part to the false lumen, 1 case of diaphragm inside tends to be the "S" shape change; There were 13 cases of external wall calcification, 6 cases of external wall calcification, 4 cases of pseudocavity wall calcification, and 3 cases of true cavity and false cavity. There were 11 cases of calcification and calcification in the inner diaphragm calcification and calcification. There were 11 cases of calcification in the inner diaphragm, 4 cases were curved to the true cavity, 1 case in the flexural cavity, 4 cases in straight lines, and 2 cases of small point calcification. One case is encircled, the lumen is the true cavity. Concluion Spider webs to AD reliable sign of false lumen, around the sign was around the cavity as the true lumen, beak sign and false cavity is greater than the true lumen, lumen thrombosis, the density of lumen strengthen contrast will aid in the identification of AD true and false lumen.