Objective To investigate the CT value in diagnosis of cavitary pulmonary aspergillosis second to obsolete pulmonary tuberculosis. Methods Chest CT data of 98 cases diagnosed as cavitary pulmonary aspergillosis second to obsolete pulmonary tuberculosis were retrospectively analyzed. Results 1 There were 104 lesions in total(43 cavity with aspergilloma and 61 cavity without aspergilloma). Comparing group cavity with aspergilloma with group cavity without aspergilloma, the characteristics consist of Simple cavity(n=26),calcification(n=27) were more common in group cavity with aspergilloma (P<0.05); and the characteristics consist of complex cavity(n=46), pleural thickening(n=14) and lesions found increased bronchial arterial blood supply and increase thick and tortuosity in CTA(n=12) were more common in group cavity without aspergilloma (P<0.05). 1 The CT signs of aspergillus inside the cavity can be subdivided into five kinds: Typical Aspergillus, Mural nodules, Cavity wall thickening, Partial soft tissue filling, and Totality soft tissue filling, and the ‘Partial soft tissue filling’ is the most commen signs (56.7%). Conclusion The CT signs of cavitary pulmonary aspergillosis second to obsolete pulmonary tuberculosis are various. To comprehensive consider the image data and clinical data which of aspergillus in different stages could raise the accuracy of diagnosis in cavitary pulmonary aspergillosis second to obsolete pulmonary tuberculosis.