【Abstract】 Objective To discuss the causes of hoarseness after thyroid surgery. Methods 508 patients with thyroid surgery, 503 patients with general anesthesia and without thyroid surgery and 100 normal people were involved in the present study. 508 patients with thyroid surgery were divided into exposure group (297 cases with exposure of recurrent laryngeal nerve) and nonexposure group (211 cases without exposure of recurrent laryngeal nerve). The anxiety of subjects was scored with SAS anxiety score. 1011 patients were divided into hoarseness group (16 cases) and nonhoarseness group (995 cases) and controlled with normal volunteers (control group, 100 cases). The effect of psychological factors, operation and tracheal intubation on hoarseness was analyzed. The patients were followed up to observe the recovery of hoarseness.Results The incidence of hoarseness of exposure group and nonexposure group were not different (P＞005). SAS score of hoarseness group was higher than that of nonhoarseness group (P＜005). SAS score of hoarseness group and nonhoarseness group were higher than that of control group (P＜005). The hoarseness might induce by general anesthesia, because there were hoarseness patients in general anesthesia and without thyroid surgery. Conclusion Exposure of recurrent laryngeal nerve in thyroid surgery cannot significantly reduce the rate of hoarseness. The causes of postoperative hoarseness is not only recurrent laryngeal nerve damage, but also the vocal cord disease, endotracheal intubation and preoperative psychological factors.