Objective To analyze the CT features of solitary pulmonary nodules(SPN) in patients with malignant tumor with the aim of improving its diagnosis and differential diagnosis in this special background .Methods From May 2014 to De-cember 2018, the CT data of 76 pathologically confirmed SPNs in patients with malignant tumor were retrospectively analyzed . The CT features of SPNs, including density, morphology and change of peripheral lung field and adjacent structures, were mainly analyzed.The characteristics of different types of nodules and their differences were summarized .Results Among the 76 SPNs, there were 41(53.9％) primary lung cancers, 14(18.5％) metastatic tumors, and 21(27.6％) benign lesions(in-cluding 12 inflammatory nodules, 7 tuberculous nodules and 2 benign tumors).Of all nodules, there were 57(75％) solid nodules, including 23(40.4％) primary lung cancers which mainly manifested as nodules with rough margin , close to adjacent vessel and bronchus and usually had internal or edge features(19, 82.6％), 14(24.6％) metastatic tumors which mainly showed as round or oval, homogeneous density, smooth margin nodules(12, 85.7％), and 18(31.6％) inflammatory nodules which mainly showed as lesions with rough and blurred margin accompanied by peripheral patch or fibrosis (14, 77.8％). There were 19(25％) sub-solid nodules, including 18(94.7％) primary lung cancers, which mainly manifested as nodules with heterogeneous density and clear border(14, 77.8％).There was only 1(5.3％) sub-solid inflammatory nodule.Conclu-sion The pathological nature of SPNs in patients with malignant tumors is various .Understanding their CT characteristics is helpful for diagnosing and differentiating and providing useful information for further treatment .