Abstract： Objective： To observe the effect of transcutaneous electrical acupoint stimulation(TEAS) on postoperative delirium(POD) in patients undergoing heart valve replacement under cardiopulmonary bypass. Methods： 45 patients undergoing heart valve replacement under cardiopulmonary bypass were randomly divided into three groups： observation group， control group 1 and control group 2. In the observation group， Shenting point(DU24) and Dazhui point(DU14) were electrically stimulated 30 min before anesthesia induction to the end of operation. The mode was 2/100 Hz density wave. The stimulation intensity was 5- 20 mA based on the acid swelling feeling that the patient could tolerate. In control group 1， shenting point and Dazhui point were 2 cm to the left，and the method was the same as that in the observation group. In control group 2，electrodes were pasted at Shenting and Dazhui points and connected with percutaneous acupoint electrical stimulator，but no stimulation was given. The occurrence of delirium at 1，2 and 3 days after operation was evaluated. The cardiopulmonary bypass time， aortic occlusion time， operation time， total intraoperative volume and anesthetic dosage were recorded. Postoperative tube time，stay time in intensive care unit(ICU)，length of hospital stay and dosage of fentanyl and midazolam were recorded. The level of serum interleukin-6(IL-6) was detected by enzyme-linked immunosorbent assay (ELISA) at 1 and 3 days after operation. Results：POD lasted for 2 days in control group 1 and control group 2；One patient in control group 2 developed delirium 3 days after operation. Both the incidence of delirium and the total incidence of delirium in the observation group 1- 3 days after operation were lower than those in control group 1 and control group 2， and the difference was not statistically significant(P=0.66). The average level of IL-6 in the three groups was higher than that before operation(P＜0.05). The level of serum IL- 6 in the observation group was lower than that in control group 1 and control group 2 at 1 day after operation， which was significantly different from that in control group 2(P＜0.05). There was no significant difference in intraoperative indexes and intraoperative anesthetic dosage among the three groups(P＞0.05). There was no significant difference in postoperative indexes among the three groups(P＞0.05). Conclusion：TEAS does not reduce the incidence of POD in patients undergoing cardiac valve replacement under cardiopulmonary bypass， but can inhibit the perioperative inflammatory response.