Abstract: The excavation of deep foundation pit is a very complex project, in the design and construction of foundation pit, should not only consider the security and stability of retaining structure, should also consider the effect of groundwater on the stability of foundation pit and the complexity of the engineering properties of rock and soil. In a foundation pit in Nanjing as the object, the selection of deep excavation and retaining structure is analyzed, summarized the key calculation and checking the content design of retaining of deep foundation pit. Finally comparative analysis of the calculation results with the monitoring data show the effectiveness of the results, the envelope form, can provide some reference for future similar project.