Abstract: Large spacecraft are subject to complex vibration environments during transportation, launch, and flight, and are typically tested using electrodynamic shaker systems before delivery. To ensure the rated performance of the shaker and reduce the impact on the surrounding environment, the design principles, structural configurations, and environmental effects of vibration-isolation foundations for large electrodynamic shakers are investigated. Taking a 35 t-class shaker foundation as a case study, scheme design, numerical simulation, and experimental verification were carried out. The results show that with the proposed isolation scheme combining a reaction-mass foundation and air springs, the first-order natural frequency of the foundation is below 1.4 Hz, and the vibration acceleration measured at 1 m from the foundation remains below 0.05g, demonstrating satisfactory isolation performance. The proposed scheme can effectively mitigate the interference of vibration testing on the surrounding environment and precision equipment, and provides a reference for the engineering design and frequency-response optimization of vibration-isolation foundations for large electrodynamic shakers.