This study is intended to propose RC vibration isolation unit as a new vibration reduction method to mitigate the ground vibration around Shinkansen viaducts induced by running high-speed trains in both vertical and lateral directions. The RC vibration isolation units can work as the vibration source isolation, propagation path obstruction or vibration receiver isolation to reduce the train-induced ground vibration by interception, absorption, scattering and diffraction of the vibration waves. Their vibration characteristics and vibration screening efficiencies are investigated by a developed 3D numerical approach with taking into account the train-bridge interaction and the soil-structure interaction. The results indicate that the RC vibration isolation units are very effective to reduce the train-induced ground vibration.