Abstract: Objective To investigate the effects of thoracic sympathetic modulation on the therapy efficacy,postoperativesympathetic arousal level and T lymphocyte subsets in patients with primary palmar hyperhidrosis. Methods From July 2014 to September 2015,40 patients with primary palmar hyperhidrosis who were prepared for thoracic thoracic sympathectomy(Group P) and 30 outpatient healthy volunteers(Group C) were recruited in the First Hospital of Jiaxing.The venous blood samples were prepared before the operation(T0),10 minutes,24 h,48 h,72 h after the operation(T1,T2,T3,T4) at Group P,while before the operation(T0) at Group C,for determination of plasma cortisol,epinephrine,norepinephrine,T-lymphocyte subsets and CD4⁺/CD8⁺ ratio. Results In group P,Oximetry-derived perfusion index raised(8.70±1.10) times and the average temperature of hands raised(2.92±0.86)℃ times,and the symptoms of hyperhidrosis disappeared in both hands.All of the patients with palmar hyperhidrosis were cured within 6 months,and the recurrence rate within 1 year was 7.5%(3/40).There was no severe complication.Theplasma levels of cortisol,epinephrine and norepinephrine at T1,T2,T3 and T4 were significantly decreased after the treatment in the group P(P<0.05),but not in the group C(P>0.05).CD3⁺,CD4⁺ and CD4⁺/CD8⁺ at T1,T2,T3 and T4were significantly increased,while CD8⁺ significantly decreased after the treatment in the group P(P<0.05),but not in the group C(P>0.05). Conclusion Thoracic sympathetic modulation may reduce postoperativesympathetic arousal and improve cellular immune function of patients.