Objective: This study was conducted to explore the possible correlation between some gene related to pain sensation and individual basal pain perception and postoperative pain intensity in the general population. Methods: Patients receiving elective surgery under general anesthesia were recruited into this study. The investigators measured their preoperative pressure pain threshold (PPT) and pressure pain tolerance (PTO). Pain intensity at rest and movement after the operation was evaluated . And the PCA drug consumption were recorded. Also there were healthy college students volunteer be recruited into this study. The investigators measured their experimental pain sensitivity including pressure pain threshold (PPT) and pressure pain tolerance (PTO), etc. Then genotyping was carried out.