Objective To evaluate the preoperative diagnosis value of fine-needle aspiration（FNA）cytological examination combined with the detection of BRAFV600E gene mutation in benign and malignant thyroid micronodules of ACR TI-RADS 5 with diameter≤5 mm . Methods The results of FNA cytological examination and BRAFV600E gene mutation detection in 75 patients with 96 thyroid nodules (TR 5 and diameter≤5 mm) before operation were retrospectively analysed. Postoperative pathological examination was regarded as the gold standard, the diagnostic performance of FNA cytological examination, BRAFV600E gene mutation detection and two methods combined in the differential diagnosis of benign and malignant thyroid micronodules was comparatively analyzed.?Results The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of FNA cytological examination combined with the detection of BRAFV600E gene mutation were 95.0%、93.8%、91.7%、95.0%、91.7%，, the area under the receiver operating characteristic (ROC) curve was 0.933. The sensitivity、accuracy、negative predictive value and the area under the ROC curve of FNA cytological examination combined with the detection of BRAFV600E gene mutation was significantly higher than that of FNA cytological examination or BRAFV600E gene mutation detection alone（P＜0.05）. Conclusion FNA cytological examination combined with the detection of BRAFV600E gene mutation can improve the preoperative diagnosis efficiency of TR 5 thyroid micronodules with diameter≤5 mm , and can reduce the occurrence of missed diagnosis. FNA thyroid micronodules combined with the detection of BRAFV600E gene mutation can not only improve the puncture accuracy, but also help to strive for the best therapy period and to determine the best surgical plan for the special location and multifocal thyroid nodules with the diameter≤5 mm.