Objective:To observe the effects of transcutaneous electrical acupoint stimulation (TEAS) on gastric emptying in patients undergoing selective surgery based on velocity of gastric emptying by ultrasonography. Methods:A total of 75 patients with selective operation of subarachnoid block at lower limb in the afternoon were randomly assigned to a TEAS group, a sham group and a control group, 25 patients in each one. All the patients were provided with semi-fluid diet at 8 a.m. The TEAS group was treated with TEAS 5 min after semi-fluid diets at bilateral Zusanli (ST 36) and Neiguan (PC 6) for 30 min, with frequency of 5 Hz and intensity which was 1 mA lower than the tolerance threshold. The sham group patients were stimulated at the same acupoints with current intensity which was 1 mA lower than the sensory threshold. The control group received no treatment. On the day of operation, and ultrasonography was given at time of empty stomach (T0), immediately after the semi-fluid diets (T1), and every 30 min after diets (T2-T6), respectively, to measure the gastric content and emptying time at semire-clining position and right lateral position. Results:The volume of gastric content in the three groups at T3-T6 was significantly less than that at T1 (all P<0.05). The volume of gastric content at T4-T6 at semire-clining position in the TEAS group was significantly less than that in the control group and sham group (all P<0.05). The volume of gastric content at T5-T6 at right lateral position in the TEAS group was significantly less than that in the control group and sham group (all P<0.05). The gastric emptying time in the TEAS group was significantly less than that in the control group and sham group (both P<0.05). Conclusion:The gastric emptying velocity could be evaluated by ultrasonography. TEAS could improve the velocity of gastric emptying and reduce the gastric emptying time.