Objective To compare the difference of thermal damage to pulmonary hilar vessels between ultrasonic scalpel and electrocoagulation hook in thoracoscopic lymph node dissection for lung cancer, and optimize the safety gear parameters. Methods A retrospective study was conducted on 100 patients who underwent thoracoscopic lung cancer surgery in the thoracic surgery department of Henan Hongli Hospital from January 2024 to June 2026. These patients were divided into three groups based on the energy devices and settings used during the operation: the 5-gear ultrasonic scalpel group (60 W, n＝50), the 3-gear ultrasonic scalpel group (40 W, n＝30), and the electrocoagulation hook group (30 W, n＝20). During the operation, infrared thermal imaging was used for temperature measurement. The Arrhenius model was introduced to convert the cumulative equivalent minutes at 43 ℃ (CEM43). The incidence of thermal damage to pulmonary hilar vessels, intraoperative indicators (peak temperature of the pulmonary hilar vessels surface, intraoperative blood loss), postoperative complications and comprehensive performance of the gear parameters among the three groups were compared. Results The incidence of thermal damage to pulmonary hilar vessels in the 5-gear ultrasonic scalpel group was significantly lower than that in the electrocoagulation hook group (P＝0.011). The intraoperative blood loss was the least in the 5-gear ultrasonic scalpel group and the highest in the electrocoagulation hook group (P＜0.001). The peak temperature on the surface of the pulmonary hilar vessels in the electrocoagulation hook group was significantly higher than that in the 3-gear ultrasonic scalpel group (P＜ 0.001), but slightly higher than that in the 5-gear ultrasonic scalpel group. The thoracic drainage volume on the first day after the electrocoagulation hook group surgery was significantly higher than that of the 5-gear ultrasonic scalpel group (P＜0.001). There were 5 cases (25.00%) of chylothorax and 3 cases (15.00%) of reoperation in the electrocoagulation hook group, which were all higher than those in the other ultrasonic scalpel groups (all P＜0.05). The comprehensive performance evaluation showed that 4-5 gear (50-60 W) of ultrasonic scalpel was the optimal parameter. Conclusion The risk of thermal damage to pulmonary hilar vessels caused by the ultrasonic scalpel during thoracoscopic lymph node dissection for lung cancer is significantly lower than that caused by the electrocoagulation hook. Parameters of 4-5 gear are recommended as a balance between safety and operational efficiency.