People with recurrent laryngeal nerve injury can have hoarseness. Observation of the voice after thyroidectomy can determine whether there is intraoperative recurrent laryngeal nerve injury. The left recurrent laryngeal nerve curves around the arch of the aorta to its posterior aspect and crosses the inferior thyroid artery posteriorly; the right recurrent laryngeal nerve curves around the subclavian artery to its posterior aspect and crosses the inferior thyroid artery anteriorly, and then the right and left recurrent laryngeal nerves travel in the tracheo-esophageal groove. The recurrent laryngeal nerves innervate all the internal laryngeal muscles except the cricothyroid muscle. Injury to the recurrent laryngeal nerve is a common complication of thyroid surgery because the inferior thyroid artery is ligated and the back of the thyroid gland is stripped from the trachea during thyroidectomy. Damage to one recurrent laryngeal nerve can lead to hoarseness, and damage to both recurrent laryngeal nerves can lead to loss of voice and difficulty breathing. Observation of the voice after thyroid surgery is in observing the presence or absence of injury to the recurrent laryngeal nerve. It is recommended that patients undergoing thyroid surgery pay attention to their voice, breathing and drinking water for choking after surgery, and inform the surgeon promptly if there is any.