Objective: To investigate the effect of use of Focus ultrasonic scalpel on the protection of parathyroid gland (PT) during thyroid surgery. Methods: Ninety-six patients with thyroid cancer undergoing thyroidectomy from August 2011 to May 2015 were selected, and randomly designated to observational group and control group, with 48 cases in each group. Patients in observational group underwent surgery by using Focus ultrasonic scalpel while those in control group using traditional monopolar electrocautery. The relevant surgical variables, the parathyroid hormone (PTH) and Ca2+ levels before and after surgery as well as the incidence of postoperative PT injury between the two groups of patients were compared. Results: The surgical variables that included operative time, length of incision, intraoperative blood loss and postoperative drainage volume in observational group were all significantly superior to those in control group (all P<0.05). there was no significant difference in preoperative PTH and Ca2+ levels between the two groups (both P>0.05), but the postoperative PTH and Ca2+ levels were significantly higher in observational group than those in control group (both P<0.05). The incidence of postoperative PT injury in observational group was significantly lower than that in control group (4.2% vs. 16.7%, P<0.05). Conclusion: Application of Focus ultrasonic scalpel has proven effect on PT protection in thyroid surgery, and is helpful for preventing the occurrence of PT hypofunction.