In order to realize the small displacement of the isolation layer in the isolation structure of the nuclear power plant in the static load stage and the good shock absorption effect in the dynamic load stage，a high-static-low-dynamic three-dimensional isolation system for nuclear power plants is proposed, which is composed of a horizontal isolation unit and a high-static-low-dynamic isolation system. The high-static-low-dynamic isolation system is composed of inclined rubber bearings and negative stiffness devices. Based on the deformation characteristics of the inclined rubber bearing and the negative stiffness device in the static load and dynamic load stages, the vertical theoretical model of the high-static-low-dynamic three-dimensional isolation system of the nuclear power plant is proposed. The inclined rubber bearing, negative stiffness device and high static and low dynamic isolation system were statically tested. The results show that the inclined rubber bearing has effective bearing capacity and high stiffness. The negative stiffness device exhibits obvious negative stiffness characteristics. The high-static-low-dynamic isolation system has a full hysteresis curve in the dynamic load stage and low stiffness. The comparison between the theoretical model and the test results shows that the proposed theoretical model of the high-static-low-dynamic isolation system can effectively reflect the mechanical characteristics of the system. The seismic response analysis of the high-static-low-dynamic three-dimensional isolation structure of the nuclear power plant shows that the displacement of the isolated structure under static load is 102.02 mm. The three-dimensional acceleration of the superstructure and internal equipment has an effective shock absorption effect, and the shock absorption rate exceeds 40%, which improves the safety of the nuclear power plant structure under the action of three-dimensional earthquakes.