Objective To investigate the MSCT features and pathologic foundation of pulmonary focal ground glass opacity (fGGO). Methods Clinical data of 75 fGGO patients treated in our hospital from January 2015 to March 2016 were analyzed retrospectively, including 21 cases benign lesions (15 cases pneumonia, 6 cases atypical adenomatous hyperplasia(AAH)) and 54 cases malignant lesions (37 cases bronchioloalveolar carcinoma (BAC), 17 cases adenocarcinoma). MSCT features of benign and malignant lesions were analyzed, including location, size, shape, border, interface, common signs, type). Results Compared with malignant lesions patients, the age and lesions size in benign lesions patients were small (P＜0.05). Malignant lesions shapes were mainly round or oval; the lesions edges were mainly lobular, spur, horn-like projection; the focal lung interfaces were clear; bronchial inflation sign, vascular bundle sign, pleural indentation sign were common in malignant lesions. There were significant differences between malignant and benign lesions (P<0.05). Most of benign lesions were type I, and malignant lesions were mainly type II / III, there were significant differences (P<0.05). Conclusion The characteristics of MSCT were related to pathologic basis. Lesion size, shape, edge, focal lung interface, typing, bronchial inflation sign, vascular bundle sign, pleural indentation sign, are important basis for the differential diagnosis of malignant and benign lesions.