Abstract: In the engineering design of modal analysis for the foundation of Centrifugal Hypergravity and Interdisciplinary Experiment Facility (CHIEF) to obtain structural dynamic characteristics, as the equipment foundation is deeply embedded, the restraint effect of side soil on the structure must be fully considered. According to the properties of different layers of soil, the linear spring element was used to simulate the boundary conditions of each contact surface between foundation and soil, and five different bases such as lateral loading test were used to take the value of spring stiffness. The calculation results of the five groups of models were similar, and the discrete deviation of the results was small, which led to more reliable modal analysis results. Further, the sensitivity analysis of the stiffness of the boundary spring on the side of the foundation structure was carried out, and the tangential constraint of soil on the foundation structure was considered by the tangential spring. Through the numerical results, the influence of the side soil boundary on the natural frequency of each section of the hypergravity centrifuge foundation in the project was more comprehensively grasped, so as to guide the blueprint design and avoid invalid investment.