Objective To explore the relationship between external branch of superior laryngeal nerve (EBSLN) injury and the approachs of surgery in open thyroidectomy, and to summarize the preventive methods. Methods The clinical data of 985 patients who had consecutively underwent open thyroidectomy from January 2009 to June 2012 were retrospectively analyzed, to explore the relationship between EBSLN injury and the approachs of surgery in open thyroidectomy. Results The overall incidence of EBSLN injury was 2.6% (26/985), and 959 patients (97.4%) didn’t suffered from EBSLN injury. Results of logistic regression showed that the extent of surgery (OR=4.536, P=0.004) and identification of the EBSLN (OR=0.126, P=0.044) were influence factors of EBSLN injury after open thyroidectomy, but age (OR=1.108, P=0.823), gender (OR=0.604, P=0.260), benign or malignant tumor (OR=1.871, P=0.186), anesthesia methods (OR=0.659, P=0.372), and the application of ultrasonic scalpel (OR=0.473, P=0.248) were not associated with EBSLN injury. Conclusion In open thyroidectomy, the extent of surgery and identification of EBSLN are the independent factors of EBSLN injury, which are important to avoid EBSLN injury.