In order to improve the seismic performance of retainer for small and medium-span bridges in China, to ensure the stability of the substructure of bridges in small and medium earthquakes, and to prevent the main girder from falling girder damage or adverse effects on the substructure due to the change of retainer stiffness in large earthquakes, a new type of seismic retainer is designed based on the concept of “fuse” and the negative Poisson’s ratio of tensile and expansion and energy-consuming characteristics. A new type of seismic retainer is designed based on the concept of “fuse” and negative Poisson’s ratio tensile expansion and energy dissipation characteristics. Firstly, the design value of the stiffness of the retainer is obtained by Midas Civil; then the force-displacement curve is obtained from the proposed static analysis of the retainer using Abaqus, and then the relevant parameters of the retainer are studied; finally, the simplified mechanical model is applied to Opensees to conduct seismic response analysis, so as to verify the seismic performance of the retainer. By increasing the cell thickness of the concave honeycomb core, the strength of the retainer gradually increases, and the initial stiffness also increases, and the energy dissipation is better; the real bridge analysis shows that the strength of the retainer is in the elastic or rising stage under small and medium earthquakes, and the seismic response parameter becomes bigger; the retainer is in the degradation stage under large earthquakes, and the stiffness decreases, and the seismic response parameter decreases. Therefore, the concave honeycomb core retainer can realize the “fuse” performance, play the role of limiting and protecting the substructure of the bridge, and only need to replace the honeycomb core after the retainer is damaged due to the negative Poisson’s ratio tensile expansion characteristics.