Objective To observe the CT signs features in patients with ground-glass nodule (GGN) lung adenocarcinoma, and analyze the value of CT signs in the differential diagnosis of preinvasive lesions and invasive lesions of GGN lung adenocarcinoma. Methods The clinical data of 38 patients with GGN lung adenocarcinoma from January 2017 to January 2018 were retrospectively analyzed. The differences in CT signs features between preinvasive lesions and invasive lesions of GGN lung adenocarcinoma, and the differential diagnosis value of CT signs was analyzed. Results There were significant differences between the preinvasive lesions and invasive lesions of GGN lung adenocarcinoma in the lobulated sign, air bronchogram and pleural indentation (P<0.05). The critical value of pre-invasive lesions and invasive lesions of pGGN lung adenocarcinoma was 10.5 mm, and the ROC curve of lesion diameter showed the area under the curve (AUC) was 83.3%, and the diagnostic sensitivity and specificity were 73.4% and 86.7% respectively. The critical value of preinvasive lesions and invasive lesions of mGGN lung adenocarcinoma was 13.8 mm, and the ROC curve of lesion diameter showed AUC was 78.2%, and the diagnostic sensitivity and specificity were 71.3% and 75.8% respectively. Conclusion There are some differences in CT signs between preinvasive lesions and invasive lesions of GGN lung adenocarcinoma. The lesion diameter can help to distinguish pre-invasive lesions and invasive lesions of GGN lung adenocarcinoma with different properties.