Objective To explore complications of endoscopic thyroidectomy and conventional thyroidectomy and to analyze causes of them in order to reducing complications of endoscopic thyroidectomy. Methods A total of 1 112 patients with thyroid diseases from September 2008 to March 2017 in the Shanghai Tongren Hospital were collected, then were designed to endoscopic thyroidectomy group and conventional thyroidectomy group. The recurrent laryngeal nerve injury, hypoparathyroidism, postoperative bleeding, tracheoesophageal injury, poor healing of surgical wound, skin ecchymosis and subcutaneous effusion, neck discomfort, and CO2 related complications were observed. Results ① There were 582 cases in the endoscopic thyroidectomy group and 530 cases in the conventional thyroidectomy group, the baselines such as the gender, age, most diameter of tumor, diseases type, operative mode, operative time, and intraoperative bleeding had no significant differences between the endoscopic thyroidectomy group and the conventional thyroidectomy group (P>0.05). ② All the operations were performed successfully, none of patients was converted to the open operation. The rates of the recurrent laryngeal nerve injury, hypoparathyroidism, postoperative bleeding, and tracheoesophageal injury had no significant differences in these two groups (P>0.05). The rates of the poor healing of surgical wound and neck discomfort were significantly lower and the rate of the skin ecchymosis and subcutaneous effusion was significantly higher in the endoscopic thyroidectomy group as compared with the conventional thyroidectomy group (P<0.05). There were 32 cases of CO2 related complications in the endoscopic thyroidectomy group. Conclusion Results of this study show that endoscopic thyroidectomy is safe for thyroid diseases, it’s complications could be reduced by improving operation technique.