Objective    To assess the feasibility and safety of ultra-micro 5 mm single-port endoscopic thoracic sympathicotomy in selected patients with primary palmar hyperhidrosis. Methods    From March 1, 2018 to February 1, 2021, 90 patients with primary palmar hyperhidrosis who underwent ultra-micro 5 mm single-port endoscopic thoracic sympathicotomy at the Thoracic Surgery Department of the University of Hong Kong-Shenzhen Hospital. There were 47 males and 43 females, with a median age of 26.0 (22.0, 31.0) years. During the operation, T3 and/or T4 thoracic sympathetic nerve chain was transected using an ultra-micro 5 mm single-port incision near the areola or under the axilla. The surgical data of the patients were retrospectively reviewed and analyzed. Results     All patients successfully completed the operation without major bleeding during the operation and no conversion to thoracotomy. There was no death or serious complication during the perioperative period. The operation time was 43.0 (23.0, 60.0) min, and the intraoperative blood loss was 2.0 (1.0, 2.0) mL. In the perioperative period, only one patient needed a tiny chest tube indwelling. The symptoms of hyperhidrosis on the hands all disappeared after the operation. The pain score on the postoperative day was 2.0 (2.0, 2.0) points. The hospital stay after surgery was 1.0 (1.0, 1.0) d. In the first month after the operation, the symptoms of hyperhidrosis on the hands were significantly relieved compared with those before the operation. The surgical incisions healed well, the wounds were concealed, and there was no wound infection or poor healing. The patients' satisfaction with the surgical incisions was 100.0%. After the operation, 14 (15.6%) patients had mild compensatory hyperhidrosis, 5 (5.6%) patients had moderate compensatory hyperhidrosis, and no patient had severe compensatory hyperhidrosis. Overall satisfaction rate was 94.0%. Conclusion     The clinical application of ultra-micro 5 mm single-port endoscopic thoracic sympathicotomy in selected patients with primary palmar hyperhidrosis is safe and feasible. The surgical wound is extremely small and hidden, the operation time is short, the pain is very slight, and the clinical outcome is good. It can fully meet the patients' pursuit of beauty.