Abstract: The fluid-mechanical coupling function in the finite difference program FLAC3D and 3-dimentional numerical method are used to analyze different factors that affect the surrounding ground and building settlements induced by dewatering during excavation of deep foundation pit.These factors include exsiting buildings or non-buildings on the ground,different positions between buildings and the deep foundation pit,foundation characteristics(such as area,depth,stiffness,form,etc.) and interactions between adjacent buildings.The simulation results show: (a) that the additional stress field and the foundation form have influence over the estimation of ground settlement,in which the ground settlement is underestimated for buildings with shallow foundation but overestimated for buildings with pile foundation as compared without considering existing ground buildings.(b) that the largest settlement and differential settlement of a building with shallow foundation are related to the foundation depth and stiffness,i.e.for increasing foundation depth the largest settlement decreases but the largest differential settlement increases,while for increasing stiffness the both settlements decrease.(c) that the interaction between adjacent buildings depends upon the relative position of these buildings from their foundation pit,generally,the influence of interaction in the axial direction is larger than that in the direction parallel to the edge of foundation pit.