Objective To explore the clinical manifestations and diagnosis effect of CT and MRI of pulmonary cancer of mediastinal type. Methods 20 cases of patients with pulmonary cancer of mediastinal type in our hospital from May 2013 to May 2014were selected, and all of the patients were checked by the CT and MRI.The clinical manifestations and diagnosis effect of the two groups were observed and compared. Results All the 20 cases were confirmed by pathological analysis, 12 cases were central type lung cancer, and 8 cases were peripheral lung cancer.It could be observed in the margins of the outer edge was irregular, burr, lobulated, mediastinal lymph nodes appear swollen, accompanied by pulmonary atelectasis and obstructive pneumonia by the examination of CT.The MRI examination could clearly observed tumor invasion of the chest wall, pleura, thoracic vertebrae.The diagnostic sensitivity of CT and MRI were significantly higher than that of X-ray examination, the difference was statistically significant (Χ2 =10.52, P<0.05); however, CT and MRI in the diagnosis of sensitivity between the two had no significant difference (Χ2 =0.00, P>0.05). Conclusion The clinical diagnosis of CT and MRI examination in pulmonary cancer of mediastinal type can obtain different imaging findings, and the two person can diagnose higher sensitivity compare with conventional X-ray examination,and obtain good diagnosis results.