Abstract: Objective To observe the evolution of heart rate variability(HRV) in patients with primary palmar hyperhidrosis after thoracic sympathetic modulation and evaluate the effects of the thoracic sympathetic modulation on the autonomic nerve system. Methods From January,2015 to November,2015,28 patients with primary palmar hyperhidrosis who were preparation for thoracic sympathetic modulation(Group P) and 22 outpatient healthy volunteers(Group C) in our hospital were enrolled into the study.The puncture of thoracic sympathetic nerve was guided by CT through the gap of T_3-4,until the needle tip arrive at the top of the fourth ribs head.2 ml of 1% lidocaine(mixed with Iohexol injection) was injected.The fingertip perfusion index(PI) was elevated more than 5 folds,the temperature of hands increased more than 3℃(about 20 min later).Then,2.5 ml of absolute alcohol was injected adjacently to thoracic sympathetic nerves.LF,HF,TP and LF/HF were recorded at the time points of before the operation(T0),10 min(T1),24 h(T2) after the operation at Group P.LF,HF,TP,the normalized values of LF(LFnu),the normalized values of HF(HFnu)and LF/HF were recorded at the time points of before the operation(T0) at Group C. Results In Group P,Oximetry-derived perfusion index and the temperature of hands raised(7.79±0.85) times and (5.03±0.85)℃ in average,respectively.All of the patients with palmar hyperhidrosis were cured within 3 months,there were no severe complications.As compared with those at T0 in Group P,TP,HF,HFnu at T1,T2 in Group P and T0 in Group C was significantly increased,and LF,LFnu,LF/HF was significantly decreased(P<0.05);There was no significantly differences between Group P at T1,T2 and Group C at T0(P>0.05). Conclusion CT-guided thoracic sympathetic modulation can be used for treating primary palmar hyperhidrosis safely and effectively,which may reduce the tension of the postoperative sympathetic nervous system,increase the tension of the vagus nerve system and improve the balance of the autonomic nervous system.