Abstract: In the calculation of the support stiffness of the deep foundation pit retaining structure system with the top-down construction method, the structural deadweight and construction load are borne by the vertical support system, and the lateral bearing capacity Is ignored. The article intends to calculate the lateral stiffness of the vertical support system, and provides a method for calculating the lateral stiffness based on the results of numerical analysis. The method can be used to quickly calculate the lateral stiffness of various column structures in engineering. The lateral stiffness of steel pipe column and lattice column structure under different forms is numerically calculated. The corresponding lateral stiffness fitting calculation formula is given. The error between the fitting formula and the numerical calculation is between 2.50% ~9.26%. The calculation method of lateral stiffness proposed in the paper is reliable. It can be used in similar projects and can be used as a reference for deep foundation pit engineering design and construction personnel.