Foundation pits of excavated-in basin often has large area and large dredging depth，and they are often close to rivers and sea，so the precipitation of foundation pits of excavated-in basin is difficult and faces high risks.A foundation pit of excavated-in basin in Qatar Doha is super large and deep.Geological conditions of the project site are double strong permeable stratum of sedimentary sand overlying limestone.Groundwater control design of the project uses diaphragram retaining walls and deep wells.Based on the analysis of water level inside and outside the underground continuous wall，seepage flow effects of the underground continuous wall is poorer.Functions of underground continuous walls in this project only embodied in the change of seepage of some areas surrounding the underground continuous wall.Based on MODFLOW module of GMS，we calculate foundation pit precipitation of basin local area.By changing the parameters of deep well precipitation (including the pumping well number，water output and well spacing，and optimize the design of deep wells precipitation，which can be helpful to the design of foundation pit dewatering for similar projects.