Abstract： Objective:To evaluate the value of B-Raf proto-oncogene, serine/threonine kinase (BRAF) V600E mutation detection in the differentiating malignant from benign with Bethesda system for reporting thyroid cytopathology (BSRTC) categories Ⅰ and Ⅲ nodules. Methods:From January 2019 to December 2020, a total of 264 nodules from 263 patients (79 males, 184 females; median age 46 years) were retrospectively enrolled and all patients underwent BRAF V600E mutation detection, fine-needle aspiration cytology (FNAC) and thyroid nodulectomy in the Affiliated Drum Tower Hospital of Nanjing University Medical School. Thirteen nodules of 12 patients had repeat aspirate samples and 51 nodules were examined with multiple genes assay in formalin fixed paraffin embedded tissues. Taken the postoperative histopathological results as the gold standard, the diagnostic efficiency of BRAF V600E mutation was analyzed by comparing the results of multiple genes assay and BRAF V600E mutation detection of repeated puncture samples. Results:Of 264 nodules, 230 were malignant (papillary thyroid cancer (PTC)) and 34 were benign, with BSRTC categories Ⅰ (nondiagnostic) and Ⅲ (follicular lesion) nodules of 58 and 206. The sensitivities of BRAF V600E mutation detection in BSRTC categories Ⅰ and Ⅲ nodules were 77.1%(37/48) and 78.0%(142/182), the specificities were 9/10 and 91.7%(22/24), the positive predictive values were 97.4%(37/38) and 98.6%(142/144), the negative predictive values were 45.0%(9/20) and 35.5%(22/62), and the accuracy rates were 79.3%(46/58) and 79.6%(164/206). The diagnostic concordance of BRAF V600E mutation detection was 90.2%(46/51) in the preoperative and postoperative samples of 51 nodules with preoperative BRAF V600E wild type but postoperative pathology confirmed as PTC and was 11/13 in repeat puncture samples. Conclusion:BRAF V600E mutation detection is an effective diagnostic method for BSRTC categories Ⅰ and Ⅲ nodules.