Objective:To investigate pathologically the characteristics of lung cancer metastasis by mediastinal lymph node ways (N2). Methods: Of 398 lung cancer patients who underwent radical pulmonectomy and extensive lymph node dissection, 160 patients were diagnosed as with N2 metastasis, their 352 groups of mediastinal lymph nodes invaded were subject to the pathological study. Results: Evidences showed that the N2 metastasis of lung cancer was very active. It appears as single group or multi-group or jumping-form metastasis, rating 41.2%, 58.8% and 29.3% respectively. In addition, the extension of N2 metastasis was large, the most concentrated site was the 7th group lymph node (48.8%), then the 4th, 3rd and 5th group, rating 45.6%, 31.3% and 25.6% respectively. The occurrence of N2 metastasis was highly correlated with the site, size, histopathological type and the grade of differentiation of the cancer. An another feature of N2 metastasis was the invasion of metastasized lymph node into the bronchial wall, especially in adenocarcinoma. Conclusion: In order to achieve the radical removal of tumor, it is necessary to dissect the lymph nodes of the hilar and upper and lower mediastinum at the homolateral thoracic cavity actively and completely; beside, attention may be paid to the bronchial wall invasion caused by the lymph nodes metastasized.