Abstract: Based on the numerical analysis for effect of lateral displacement of supporting for pit in foundation in soft soil area,the influence of the distance is analysis between the inner and outer pits of a large pit on the horizontal deformation of the supporting structure under the two types of pits and gravity dams.The calculated results showed that the distance is the larger between the inner and outer pits,the horizontal displacement is the smaller of the outer pit,when the distance is greater than 2~3 times the pit depth,the horizontal deformation of the supporting structure can’t consider the influence of pit.The distance is the larger between the inner and the outer pits,the horizontal displacement is the smaller of the inner pit;Horizontal deformation of inner pit is affected by the stiffness of outer pit.The lateral displacement of inner supporting structure reduces with the increasing stiffness of outer supporting structure.