Objective    To evaluate the predictive value of high frequency ultrasound on the extra-laryngeal branching of recurrent laryngeal nerve.   Methods    Preoperative ultrasound data of patients undergoing thyroidectomy from December 2023 to June 2024 were collected and cross-sectional ultrasound images of lower thyroid artery (ITA) and cricothyroid  joint (CTJ) were saved to measure the maximum diameter (SD) and cross-sectional area (CSA) of the recurrent laryngeal nerve area on the above planes. The results of exploration of recurrent laryngeal nerve during thyroidectomy were used as the gold standard, the cases were divided into extra-laryngeal branching group and non-extralaryngeal branching group. Statistical differences of parameters between the two groups were compared, and the cut-off between the groups was calculated according to the Youden index.    Results   A total of 95 nerves from 76 patients were included, 19 extra-laryngeal branching nerves (accounting for 20.0%) were confirmed intraoperatively. The SD, CSA on CTJ level and the ratio of the parameters to ITA level were significantly lower in the branching group than that of the non-extralaryngeal branching group (P<0.05). The cut-off value for predicting the extra-laryngeal branching was CSA of 1.4 mm2 of the nerve (AUC=0.823) and the ratio of this parameter to ITA level was 0.78 (AUC=0.875).  Conclusions  Preoperative high-resolution ultrasound could predict extra-laryngeal branching of recurrent laryngeal nerve, and have positive significance for surgical planning and nerve protection of thyroidectomy.