〔Abstract〕 Objective To investigate the effect of intraoperative palmar temperature rising less than 1 °C on endosocopic thoracic sympathectomy (ETS) for the treatment of primary palmar hyperhidrosis (PPH). Methods From February 2018 to September 2020, 63 patients with PPH were treated with ETS in our hospital. Among of these, 18 patients treated with bilateral R3 (third rib) ETS whose palmar temperature increased less than 1 °C during operation were selected, and their clinical effects and complications were analyzed. Results The hands were warm and dry on the first day, one week and one year after operation, and the effective rate was 100.0 %. Compared with preoperatively, the remission rate of hand sweat, head sweat, and axillary sweat of the patients on the first day, week, and year after operation was statistically significant (P < 0.05); The remission rate of foot sweat on the first day after operation was compared with that before operation, the difference was statistically significant (P < 0.05), but theremission rate in the first week and year after operation was not significantly different from that before operation (P > 0.05). There were no perioperative vascular injury, Horner syndrome or massive hemorrhage,but there were 3 patients with mild pneumothorax who had lung compression of 5 % ~ 15 %,which was due to incomplete gas elimination during the operation and no treatment was required. At the twelve-month follow-up, one case required hand lotion due to excessive dry hands in winter; The total incidence of compensatory hyperhidrosis was 61.1 %. Conclusion ETS is safe and effective in treatment of PPH, even if the intraoperative palmar temperature rising is less than 1 °C.