The movement of groundwater in the permeable medium is successive. However, owing to the variation of the supply and drainage conditions, the movement of groundwater in distinct region is different. According to the formation and developing history of the groundwater system theory, this paper briefly described the characteristics of the differential movement of groundwater in uniform flow field obtained from sand tank experiments. This paper analyzed the reasons and mechanisms, and made experi ments or tests by using ‘resembling Darcy experiment device’ with different diameters. The results show that the hydraulic conductivity varies with cross-section of infiltration. The larger the cross section, the greater the hydraulic conductivity.