Objective To propose an optimal method in acquiring the volume of whole stomach (VWS) of healthy adults by ultrasound, and validate its repeatability. Related influencing factors were also explored. Methods Conventional ultrasound was conducted in 99 healthy volunteers after 500ml water-drinking immediately, among whom 20 volunteers were chosen for the repeatability validation, including inter- and intra-operators. Measurements were taken to get the area of gastric fundus, gastric body, gastric antrum in the largest short axis sections. The lengths and diameters of gastric body as well as antrum were also calipered. Assuming gastric fundus as a sphere, gastric body and antrum as cylinders, the VWS were obtained by summing up the volumes. The variable coefficients between the measurements were calculated to validate the inter- and intra-operators repeatability. The relationship between VWS and gender, age, and body mass index were also analyzed. Results 1) The gastric fundus, body and antrum were completely filled with liquid by appropriate body positions. The sections of measurements were revealed clearly. 2) The gastric fundus area, gastric body length, gastric body area, gastric antrum area, gastric antrum length could be measured by ultrasound. The intra-operator variable coefficients of the above parameters were 5.9%,14.2%,9.9%,5.7% and 6.3%, respectively. The inter-operators variable coefficients were 14.3%,14.9%,18.1%,10.6% and 18.9%, respectively. The total intra- and inter-operators variable coefficients of VWS were 5.8% and 13.7%, respectively. 3) The reference value of VWS in healthy adults after water-drinking was 656±91cm3. 4) VWS was not significantly related with gender or age, yet positively associated with body mass index. Conclusion This study established a feasible and simple method to obtain VWS with high repeatability. Body mass index was the main influencing factor for VWS in healthy adults.