Abstract: Aiming at the land-subsidence caused by groundwater dewatering in quaternary loose sediments,based on Biot’s consolidation theory,a full coupling three-dimensional mathematical model of seepage and stress was established considering the non-linear characteristics and the dynamic variation of hydraulic conductivity of soils with stress.A three-dimensional finite element analysis method was applied to the dewatering of a repair foundation pit in the forth subway of Dongjiadu tunnel of Shanghai,then it was used to simulate and forecast the distribution characteristics of groundwater seepage field and land subsidence deformation field around the foundation pit when the water table of the foundation pit center reduced to-23.4 m.It was shown that this model would speedily converged with a fine stability,and could be used to simulate three-dimensional complex geological properties and the structure of the entire dewatering project of the foundation pit.