In order to enhance the unseating prevention capacity of bridge and reduce the seismic loss of transportation lifeline system, a new control device for the seismic unseating prevention of bridges is developed according to the conceptions of energy dissipation, multi-failure and damage reduction. The device provides two different control types of performance including energy dissipation-based displacement restriction and unseating prevention, and these two level control types can be automatically transformed. Firstly, the composition, characteristics and the working mechanism of the device are analyzed. Then, a quasi-staic experiment is conducted to examine the hysteretic curve of the energy dissipation-based displacement restriction unit of the first-level control. Then, a static tensile experiment is conducted to investigate the deformation characteristics, the failure mode and the anchoring capacity of the cable restrainer unit on the second-level control. In addition, a bolt shear experiment is conducted to examine the control conversion function. Finally, our finite element simulation method is verified by the experimental results. The results indicate that the twol-evel control device for seismic unseating failure has an effective displacement constraint capacity, a reasonable energy dissipation mechanism and a distinct structure of damage-reduction fuse. The device achieves complementary advantages between its girder-girder connection and pier-girder connection control mode, providing a reliable guarantee for unseating prevention and a safety protection of bridge pier in strong earthquake.