Abstract: Objective: To discuss CT signs and differential diagnosis of peripheral lung cancer and pulmonary tuberculoma in the predilection site of pulmonary tuberculosis. Methods: 134 cases of obsolete pulmonary tuberculosis patients with the tuberculoma or tumor in the predilection site of pulmonary tuberculosis who hadunderwent CT examination over the last 6 years were collected, of which there were 80 cases with peripheral lung cancer and 54 cases with pulmonary tuberculoma confirmed by pathology. All patients were divided into two groups. Group Ⅰ were the patients with the peripheral lung cancer, and group Ⅱ were the patients with pulmonary tuberculoma. Define the cases with tuberculum or tumor with obsolete pulmonary tuberculosis which were in the different lung segment and isolated existent as groupⅠa(49 cases) and group Ⅱa(39 cases); the cases with the mixture of the tumor and obsolete pulmonary tuberculosis in the same lung segment were defined as group Ⅰb(31 cases) and group Ⅱb(15 cases). Reviewing CT images of each group, group Ⅰ and group Ⅱ data between groups and within groups were respectively tested and analyzed with chi-square criterion. Results: Group Ⅰ had the highest proportion of adenocarcinoma(61/80). There were no statistically significant differences in distribution of lesions between group Ⅰ and group Ⅱ(P ＞ 0.05). Comparing group Ⅰa with group Ⅱa, the factors(tumor diameter≥ 3 cm,uneven density, vacuole sign, shallow lobulation, enhancement ≥ 20 Hu and inhomogeneous enhancement) were more common in group Ⅰa(P ＜ 0.05); and the factors(uniform density, calcification, clear edge, enhancement ＜ 20 Hu, ring enhanced) were more common in group Ⅱa(P ＜ 0.05). Comparing Group Ⅰb with group Ⅱb, the factors(the size of tumor≥ 3 cm, uneven density, enhancement≥ 20 Hu, inhomogeneous enhancement and emphysema) were more common in group Ⅰb(P ＜ 0.05); and the facts(uniform density and enhancement ＜ 20 Hu) were more common in group Ⅱb. Comparing Group Ia with group Ⅰb, the factors(cavity and enhancement ＜ 20 Hu) were more common in group Ⅰa(P ＜0.05); the factors(calcification, enhancement≥20Hu, inhomogeneous enhancement and emphysema) were more common in group Ⅰb(P ＜ 0.05). There were no statistically significant differences between the CT signs of group IIa and group Ⅱb(P ＞ 0.05). Conclusion: CT signs of pulmonary tuberculosis patients with peripheral lung cancer and secondary tuberculosis tumor have overlapping. The comprehensive analysis of various CT signs is an important basis for the differential diagnosis.