Abstract: The use of steel sheet-pile retaining structure is restricted by field condition.The step-slope excavation is not suitable for foundation trench and it requires underground engineering construction of vertical earthwork excavation.It analyzes the main influence factors of foundation pit retaining structure earth pressure，and improves the calculation method of earth pressure in pit sheet-pile retaining structure design according to the basic principle of Rankine＇s earth pressure calculation and by means of an engineering project.