Abstract: Retaining structure with soil nailing walls which has a deformation of obvious spatial effect is the most commonly used form of foundation pit retaining structure in the Beijing area. This retaining structure usually uses the method of design that one section is applied to every part of the foundation pit; therefore, it is more unsafe and conservative relative to external corner and internal corner position. In this paper we made an analysis result with three-dimensional numerical simulation on a foundation pit in Beijing in order to study the spatial effect of deformation of the retaining structure with soil nailing walls. Through this we draw a conclusion that the maximum horizontal displacement took place in external corner of the foundation pit and around was the most unsafe position while the horizontal position of internal corner of the foundation pit turned to be significantly smaller than other parts but had little area of effect thus we could hardly consider its effects on overall deformation of the foundation pit.