The significance of numerical analysis of foundation pit excavation lies in the selection of soil constitution and reasonable input parameters.The hardening model(HS model) is one of the soil constitutive models that are widely used.In this paper, the GDS Hollow Torsion Shear Tester (SS-HCA) and consolidation apparatus were used to complete a series of laboratory tests.The parameters of the hardening model of the soft soil layer in Nanchang were obtained through the tests. The proportional relationship between the modulus of each layer of soil parameters has been discussed.The experimental results were compared with the result from literatures. Then, the PLAXIS finite element software was used to conduct numerical simulation of a certain basement deep foundation pit project in Nanchang. The soil constitutive model adopted the programmed HS model. The results show that the calculated value of the deep horizontal displacement of the retaining pile is basically consistent with the measured value. The HS model and the determination method for parameters have been proved to be applicable in numerical analysis of foundation pit excavation engineering in Nanchang area.