Abstract: 【Abstract】 Objective To determine the value of focal area of ground-glass opacity (fGGO) for early detection and diagnosis of lung cancers. Methods We reviewed clinical data of all patients whose chest CT images showed isolated lesions ≤5 cm in diameter in the Department of Chest Surgery at West China Hospital, Sichuan University between 2007 and 2010. According to the volume of solid components, the lesions were classified as pure ground-glass opacity (pGGO), mixed ground-glass opacity (mGGO) or solid lesions. The malignant ratio and stage of lesions were calculated based on the postoperative pathological tests. The characteristics of CT signs were compared between the benign and malignant lesions. Results Of the 202 cases, 63 (included 15 pGGO and 48 mGGO) had fGGO with a malignant ratio of 71.4% (45/63). The percentage of malignant tumors in the mGGO, pGGO and solid lesions was 75.0%, 60.0% and 48.2% respectively. Stage Ⅰ lung cancers had an occurrence of spiculation, lobulation and vascular convergence in fGGO of over 70%, higher than that of the benign tumors (P<0.05). Conclusion fGGO is an important indicator of lung cancer. mGGO is highly likely to be malignant, particularly when one or more signs of spiculation, lobulation and vascular convergence appear.