Intra-pulmonary ground-glass density shadow is a mild increase in density on high-resolution CT images, but the bronchial vascular bundles within it can still be shown. This sign is often a manifestation of early lung disease, and its timely detection and diagnosis is important for proper clinical management and prognosis. In recent years, the study of HRCT on peripheral type small adenocarcinoma of the lung containing GGO and severe acute respiratory syndrome has enriched the overall understanding of the imaging pathological features of GGO in the lung. Features: 1. Acute inflammation: blurred margins in patches that shrink after anti-inflammatory treatment. 2. Chronic inflammation: clear margins, irregular shape, critically connected to the pleura in a broad base, and possible high-density calcification within the lesion. 3. Alveolar blood accumulation: In patients with a history of hemoptysis, blood flows back into the alveoli and coats the alveolar wall like a spray, forming multiple patches with blurred margins that will absorb and dissipate on their own in one to two weeks. 4. Atypical hyperplasia: a spherical lesion with sharp margins and no pulling of the adjacent pleura. 5. Atypical adenomatous hyperplasia with fine bronchoalveolar cell carcinoma: lobulated spherical lesions with adjacent pleura stretched like the top of a Mongolian tent. 6. Adenocarcinoma of the lung: spherical lesion with mixed ground glass and parenchymal nodules, pleura is stretched, and parenchymal nodules are enhanced after enhancement. 7. Nodules larger than 8 mm in diameter have a high chance of malignancy and are recommended to be removed by minimally invasive thoracoscopic surgery. 8. PET-CT resolution is not enough for lesions less than 7mm in diameter, and all the ground glass shadows cannot be shown in PET-CT. 9. In general, CT scan of lungs in tertiary hospitals is 10mm thick, so the details of small lesions cannot be seen, while CT scan of lungs in large general tertiary hospitals (such as Tianjin First Central Hospital) is 5mm thick, which can sometimes be distinguished. Even available 1mm layer thickness scan, any angle three-dimensional reconstruction, very sensitive to show the fine lesions. 10. For patients who cannot be diagnosed, the doctor will also recommend a review after one month, but repeatedly repeated CT is a certain accumulation of damage to the body, it is better to review with low-dose CT, which is only 1/4 of the normal dose and safer for patients. In conclusion, detection of GGO should be treated early at a large general hospital thoracic surgery department to avoid delay.