Objective To evaluate the clinical role of video-assisted mediastinoscopy and its safety and effectiveness in the diagnosis of thoracic disease. Methods We reviewed the clinical data of consecutive 40 patients (25 males and 15 females with an average age of 54.6 years) who received video-assisted mediastinoscopic surgery in our department of thoracic surgery from December 2011 to November 2016, including mediastinal lymph node biopsy in 27 patients, mediastinal primary lesions biopsy in 8, bronchial cystectomy in 3 and esophageal dissection in 2. Results The histological results were positive in 20 patients (73.1%) in mediastinal lymph node biopsy, including granulomatous mediastinitis in 14 and metastasis in 6 (non-small cell lung cancer in 4, Ewing sacoma in 1 and small cell lung cancer in 1) and reactive proliferation in 7 (26.9%). In mediastinal primary lesions biopsy, the accuracy rate of diagnosis was 100.0%. The pathologic results were malignant in all patients, including small cell lung cancer in 5, adenoid cystic carcinoma in 1, squamous carcinoma in 1 and adenocarcinoma in 1. In patients who received the bronchial cystectomy, no recurrence was found during at least 2 years follow-up. There was one patient with severe complication (innominate artery injury). Two patients suffered transient laryngeal recurrent nerve palsy with hoarseness and two patients incision secretion. Conclusion Video-assisted mediastinoscopic surgery is effective and safe and dissection should be careful in granulomatous mediastinitis to avoid the great vessel injures.