Abstract: Objective: To evaluate the capacity of intraoperative ultrasonography （IUS） for lung cancer surgeryin detecting the lymph nodes in mediastinum and hilum.The accuracyof IUS in determining lymph nodes metastasis was also appraised. Methods: The lymph nodes were detected in every regions of mediastinum and hilumby IUS and compared with preoperative CT scan in 28 cases of lung cancer,and the number,size and location of the lymph nodes were recorded,and the metastasis oflymph nodeswere predicted by respective criteria. The mediastinumexploration and lymph nodes resection were performed in each case,and every resected lymph node was taken a pathological examination. Results: ① The sensitivityof CT and IUS in detecting lymph nodes were 73.9%（119/161）and 86.3%（139/161）respectively（P = 0.005）. ②The sensitivities of IUS （by the geometricmeasures and by characters of sonogram） and CT in diagnosing lymph nodes metastasis were 73.7%,88%,66.7%,respectively（P =0.149）;the specificities were78.3%,66.7%,75.8%,respectively（P =0.666）;theaccuracies were 68.4%,81.8%,64.7%,respectively（P =0.174）. Conclusion: IUS is a effective method for lung cancer surgery in detecting the mediastinum lymph nodes.