Objective: To investigate the effect of NBI assisted white light transurethral resection of bladder tumor (TURBT) in the treatment of bladder urothelial carcinoma and to summarize the experience of narrow band imaging (NBI) operation. Methods: Patients with bladder urothelial carcinoma were selected, and TURBT was performed after anesthesia. First of all, the bladder tumor was found and resected under white light. Then we replaced with NBI, looked for suspicious lesions and resected them, The specimens excised under white light and NBI were collected separately. The number, location and pathological results of the lesions under white light were recorded, and the residual lesions under NBI were also recorded. To evaluate the effect of NBI, the ratio of residual bladder tumor was calculated. The cases were divided into three groups according to the time sequence. The clinical data of each group were collected and the learning curve of TURBT under NBI assisted white light was observed. Results: A prospective study of 45 patients with bladder tumor from April 2018 to January 2020, including 32 males and 13 females, aged from 23 to 89 years, with an average age of 65.2 years. All the operations were successfully completed, without obvious complications after operation. Nine cases were single and 36 cases were multiple. The maximum diameter of the tumors was 0.5 to 4.0 cm, with an average of 2.2 cm. The histopathology of the resected tissue under white light was urothelial carcinoma, and 19 cases (42.2%) were pathologically positive by NBI resection. The 45 cases were divided into three groups according to the time sequence, 15 cases in each group. The true positive rate of NBI was 33.3%, 46.7% and 46.7%, respectively, and the false positive rate was 60.0%, 46.7% and 26.7%, respectively in the three groups. Conclusion: TURBT is an effective way to treat bladder urothelial cancer, NBI is an effective supplement of white light, which can increase the detection rate of bladder cancer and reduce post-operative recurrence. The NBI light source has a certain learning curve. With the increase of cases, the false-positive rate of NBI is gradually reduced. After the NBI operator has rich experience, the recognition degree of flat tumor is gradually improved under white light, and the residual rate of NBI is reduced after the removal under white light.