Abstract: Resistance tomography sensor possesses a soft field. This field is distorted by the media material distribution to be measured. Using the ERT finite element method simulation software set up by authors in NEU, the sensitivity distributions under different media distributions were calculated. The soft field characteristics of resistance tomography sensor was investigated by comparing and contrasting these sensitivity distributions. Different phase distributions can result in several tenths increase or decrease in sensitivity values. The sensitivity value chage at each pixel correlates to not only the media distribution inside the field, but also the pixel position.