In recent years, the incidence of ground-glass nodular lung adenocarcinoma has gradually increased. Preoperative evaluation of the tumor invasiveness is very important, but there is a lack of effective methods. Plasma samples of ground-glass nodular lung adenocarcinoma and healthy volunteers were collected. Pulmonary nodules with different densities were compared by metabolomics. Different invasive degrees of lung adenocarcinoma were contrasted as well. Multivariate statistical methods were applied to search for significant metabolites from comparisons between two groups. The common metabolites among the different comparisons were selected and then assessed by various indices. Five metabolites were discovered for lung adenocarcinoma with different invasive degrees. Significant metabolites were selected for pulmonary nodules with different densities as well. When these metabolites were cross-compared, only the level of lysoPC(18:3) was significantly lower in ground-glass nodular lung adenocarcinoma than healthy population, as opposed to other metabolites. After identifying the invasive degree of pulmonary ground-glass nodules, lysoPC(18:3) showed a satisfactory sensitivity and specificity, both greater than 0.85. Metabolomics analysis has favorable advantages in the study of ground-glass nodular lung adenocarcinoma. LysoPC(18:3) may have the potential to differentiate precancerous lesions from invasive lung cancer, which could help clinicians to make proper judgment before surgery.