Objective In this study, we propose three-dimensional electrical impedance tomography (3D-EIT) combined with two-dimensional electrical impedance tomography (2D-EIT) to study the electrical characteristics of gastric volume changes and the response to changes in the gastroesophageal liquid condition with the objective of investigating the possibility of applying EIT technique to monitor gastroesophageal reflux disease (GERD).Methods Eight subjects were asked to fast 4 h before the experiment to ensure that the gastric was in an emptying condition at the start of the experiment. The subject was asked to drink 400 ml of rehydration water in two parts, 3D-EIT was applied to detect the conductivity distribution in the 3D space of the abdominal cavity at the condition of 200 ml intake and at the condition of 400 ml intake, respectively. In order to quantify the variation of electrical characteristics in different conditions, the spatial-mean conductivity () of 3D-EIT was analysed by using a paired-samples t-test. In addition, numerical simulation tools were used to establish two sizes of gastric volume models to verify that the cause of conductivity changes in the 3D space of the subject’s abdominal cavity in the experimental results is due to the changes in gastric volume. The trends of electrical characteristics when gastric cavity was filled with different ratios of rehydration water were investigated, and 2D-EIT numerical simulation was applied to reconstruct the conductivity distribution image σ.Results The results of the paired-sample t-test for spatial-mean conductivity ) in the abdominal 3D-EIT experiment in eight subjects show that the spatial-mean conductivity increased from ^{200 ml}=0.226 in the C^{200 ml} case to ^{400 ml}=0.387 in the C^{400 ml} case (n=8, P<0.05). Thus, the of subject’s abdominal gastric region increased significantly with increasing gastric volume. The 2D-EIT numerical simulation results show that the measured voltage difference (ΔV) is decreased gradually with increasing the rehydration water ratio of the gastric lumen filling. ΔV is sensitive to the ratio of gastric lumen filling rehydration water. The average voltage difference is smaller in the big gastric lumen model with the same ratio of gastric lumen filling rehydration water compared to the small gastric lumen model. is sensitive to the size of gastric lumen model. In the small gastric lumen model, the spatial-mean conductivity is increased with the ratio of gastric lumen filled with rehydration water, from _A=-0.29 for 25% filling to _D=-0.41 for filling 100%; in the big gastric lumen model, the is also increased with the ratio of gastric lumen filled with rehydration water, from _E=-1.85 for 25% filling to _H=-2.12 for filling 100%.Conclusion The 3D-EIT satisfactorily monitors the differences in electrical characteristics of different gastric volumes by 3D-EIT images. 2D-EIT shows the same trend according to ΔV, , and in different gastric volume models. Therefore, we conclude that 3D-EIT combined with 2D-EIT technique satisfactorily monitors liquid condition changes in the different gastric volumes.