Objective To investigate whether the pleth variability index, a noninvasive and continuous tool,can predict the nociceptive stimulus. Methods Patients with ASA status Ⅰ~Ⅱ undergoing gastric operation were randomly divided into two groups: tracheal intubation general anesthesia (group GA) and combined general-epidural anesthesia (group GE) in 30 cases. Heart rate(HR),mean arterial blood pressure(MBP),perfusion index（PI）,pleth variability index(PVI) were recorded before and after tracheal intubation and skin incision. Results HR and MBP in both groups increased after endotracheal intubation, but no significant differences. PI decreased significantly after endotracheal intubation [from (2.63±0.54) to (0.94±0.23) in group GA, (2.63±0.44) to (0.93±0.23) in goup GE,P<0.05], while PVI increased significantly in both groups [from (11.07±2.56) to (21.50±3.44) in goup GA,(10.80±2.78) to (21.77±3.07) in group GE,P<0.05]. PI decreased significantly after skin incision in group GA [from (2.67±0.62) to (0.77±0.28),P<0.05], but PVI increased significantly [from (10.80±2.57) to (23.70±3.63),P<0.05]. Both PVI and PI have no significant change in Group GE after skin incision.The skin incision did not affect the HR and MBP in two groups. Conclusion PVI can reflect the patient's noxious stimulation rapidly and accurately.