Abstract: A 3D FEM program was used to analyze the seismic behaviors of wall confined soils of underground.Taking 1995 Kobe Earthquake waves as input and assuming that the ground was composed of medium dense sand and loose sand,it was shown that horizontal displacement of the enclosed medium dense soils decreased as a result of wall confinement.The excess pore water pressure of the confined soils was strongly excited due to soil-structure interaction.However,the development of excess pore water pressure of confined soils reduced with the decrease of distance between two sides of the wall,especially in the case of medium dense sand.The sudden drop of development of excess pore water pressure of medium dense sand took place due to soil dilantancy and the confinement effect greatly reduced the occurrence of the soil liquefaction in enclosed area.