This study is aimed to investigate the structural safety of bridges with rocking isolation of spread foundations under extreme earthquakes by using dynamic analysis. The vector form intrinsic finite element is adopted to simulate the failure procedure of bridges with and without rocking isolation. A practical five-span bridge with spread foundations is chosen to study the effect of rocking isolation.A parametric study is conducted to realize the effect of various sizes of footings under various soil conditions. The analytical results show the effectiveness of rocking isolation of bridges under large earthquakes. As the soil stiffness decreases, the rocking response of the foundation increases so that the seismic response of the bridge decreases. While the size of the footings decreases, the bridge exhibits smaller seismic response and collapses at higher ground motion. To maximize the effect of rocking isolation, it is needed to design both the column and foundation in optimum sizes.