Abstract: Objective Retrospective analysis the CT features of cavitary tuberculosis and peripheral lung cancer with cavity formation, to improve the understanding and CT diagnosis of these two diseases.Methods Twenty-two cases of pathology-proved cavitary tuberculosis and 24 cases of pathology-proved peripheral lung cancer with cavity formation were collected from August 2011 to October 2014 by some hospitals in Dalian, all the clinical information and chest CT examination were collected. To analysis the CT features differences between the two groups, independent sample t test and Pearson χ² test were used, P<0.05 was considered statistically significant.Results The mean age of cavitary tuberculosis (43.59±13.16 years) was lower than lung cancer group (62.92±10.21 years) (t=5.591, P<0.001); The right lung was more vulnerable to occur these two diseases than the left lung (number of cases in right lungs/number in left lungs was “14/8” and “15/9” respectively), but not statistically significant (χ²=0.006, P=0.936). The emergence ratios of irregular cavity [41.7% (10/24)], unsmoothed inner wall [62.5%(15/24)], inner wall nodules [45.8% (11/24)], vascular within the lesion [41.7% (10/24)] and lobula-ted sign [20.8% (5/24)] in the lung cancer group were greater than cavitary tuberculosis group [13.6%(3/22), 27.3% (6/22), 18.2% (4/22), 0.0% (0/22) and 0.0% (0/22) respectively] (χ² values were 4.448, 5.741, 6.379, 1.713, 5.124, P<0.05); but the “satellite lesions” sign proportion of cavitary tuberculosis group is greater than the lung cancer group [they were 68.2% (15/22) and 0% (2/24) respectively](χ²=24.282, P<0.001).Conclusion CT features were different between cavitary tuberculosis and peripheral lung cancer with cavity formation, the cavity appearances and “satellite lesions” sign contribute to the differential diagnosis of the two diseases.