The excessive deformation of the foundation pit supporting structure seriously affects the safety of the foundation pit and the surrounding buildings.The proved influencing deformation factors have important guiding significance for design and construction safety.Taking the foundation pit project of a deep soft soil lock as an example,we use the finite element software to build a three-dimensional model to simulate the excavation process,study the influence law of the soil parameters,edge load,the reinforcement strength of soil between piles and pile stiffness factors on the deformation of the supporting structure,and use the grey relational analysis(GRA)to analyze the sensitivity degree of each influencing factor.The results show that when the friction angle in the soil drops or the load increases,the horizontal displacement of the pile top increases significantly.The horizontal displacement of pile top to various factors is soil parameters,edge load,soil reinforcement strength and pile stiffness.In the design and construction of deep soft soil foundation pit,attention should be paid to deformation and rheology of soft soil,improve soil strength and to reduce the external load of supporting pile,so as to ensure the safety of foundation pit engineering and surrounding buildings.