Abstract: Isolation efficiency and dynamic response of base-isolated structure are certainly influenced by the soft interlayer foundation conditions. Based on the model shaking table tests, the earthquake response characteristics of the soft interlayer foundation, base-isolation system and isolation structure under different spectral characteristics and intensities of input ground motion are analyzed and compared. The earthquake response characteristics and rules for the soil-isolated structure dynamic interaction system are obtained. The results show that the model foundation can reflect the earthquake response characteristics of soft interlayer foundation. At the same time, the spectral characteristics and intensities of input motion have significant impacts on the efficiency of isolation layer and the change law along the vibration response of base-isolated structure. The main reason is that the characteristics of the input motion are changed obviously by the soft foundation, which plays the role of a natural isolation layer for the upper structure.