Lung glandular precursor lesions mainly refer to atypical adenomatous hyperplasia and adenocarcinoma in situ, which are precancerous lesions of invasive carcinoma of the lung, both of which may present as ground glass nodules. Lung glandular precursor lesions, also known as pre-invasive lesions, mainly include atypical adenomatoid hyperplasia and adenocarcinoma in situ, which are mainly distinguished from infiltrative lesions including microinvasive adenocarcinoma as well as invasive adenocarcinoma. Atypical adenomatoid hyperplasia is a precancerous lesion of bronchoalveolar carcinoma and peripheral adenocarcinoma, and is an atypical hyperplasia of the walls of the alveoli of the respiratory or terminal bronchi. The atypical hyperplasia may progress from mild to severe, i.e., the cells of the atypical hyperplasia gradually involve the whole alveolar epithelium, and some of them eventually progress to bronchoalveolar carcinoma or peripheral-type lung adenocarcinoma. Adenocarcinoma in situ is a precancerous lesion of lung adenocarcinoma, which means that the heterogeneously proliferating cells involve the whole layer of glandular epithelium, and it is more often shown as a pure ground-glass nodule of 5~30mm in chest CT, and it is less likely to have signs such as burr, lobulation, pleural pulling, etc., and it has slightly higher density with atypical adenomatous hyperplasia. Pre-infiltrative or precursor lesions do not belong to the category of malignant tumors, so most of them do not require surgical treatment, but there is a risk of malignant transformation that requires close follow-up observation. Patients are advised to consult their specialists and follow up and treatment as prescribed by their doctors.