Objective To evaluate the application value of narrow band imaging video-bronchoscopy in diagnosis of lung diseases. Methods 122 cases of patients suffered lung diseases were checked by narrow band imaging bronchoscopy, whose NBI images were analyzed and scored, then comparison between benign diseases and malignant diseases were made. The specificity, sensitivity, positive and negative predictive values of NBI in revealing lung cancer were compared with white light bronchoscopy. Results In the biopsy group there were significant difference between the benign group (NBI score 9～11) and the malignant group (NBI score 13～14). The specificity ,sensitivity, positive and negative predictive values of NBI in revealing lung cancer were 93.5 %, 92.6 %, 87.8 % and 96.2 %, respectively, while white light bronchoscopy were 84.8 %, 54.7 %, 38.6 % and 91.5 %, respectively, there were significant difference between the two techniques (P < 0.05, P < 0.001, P < 0.001 and P < 0.05, respectively). Conclusion Compared with white light bronchoscopy, narrow band imaging vedio-bronchoscopy had better specificity, sensitivity, positive and negative predictive values in the assessment of lung cancer, and it might play a significant role in the therapeutic decision.