Abstract: Based on the features of the shield building for AP1000 nuclear power units, the optimal model of the shield building for stiffness and damper is given, and the new structural system with inter-story isolation is established by modifying the connection between different parts of the shield building. By comparing with the seismic responses of the traditional model and the base isolation model, the different vibration mechanism of the inter-story isolation model is shown obviously, and its earthquake resistant behaviors (i.e., reduction effect stability, anti-seismic robust, and adaptive site) are presented.